WORD PROBLEMS
INVOLVING EQUATIONS IN
ONE VARIABLE
(AGE PROBLEMS)
Example #1: Vio is now 24 years older than his brother.
Find their present ages if he will be twice as old as his
brother in 6 years.
Representation
:
x = present age of Vio’s
brother
Present Future
Vio
brother
x + 24
x
(x + 24) + 6
x + 6
Equation: (x + 24) + 6 = 2 (x + 6)
Example #2: The sum of the ages of Kerby and his
cousin is 42. How old is Kerby if he is 8 years younger
than his cousin?
Representation
:
x = present age of Kerby’s cousin
Present
Kerby
cousin
x - 8
x
Equation: x + (x – 8) = 42
Example #3: Six years ago, Eizen was 12 year younger
than twice his sister’s age. How old is Eizen if he is
thrice as old as his sister now.
Representation
:
x = present age of Eizen’s
sister
Present Past
Eizen
sister
2x
x
2x - 6
x - 6
Equation: 2x – 6 = 3 (x – 6) - 12
WORD PROBLEMS
INVOLVING EQUATIONS IN
ONE VARIABLE
(DIGIT PROBLEMS)
Example #1: Find the two-digit number if the sum of
its digits is 8. The number is 11 times its units digit.
Representation
:
x = units digit
Equation: 10 (8 – x) + x = 11x
8 - x = tens digit
Example #2: The number is more than three times the
sum of the digits. Find the two-digit number if the tens
digit is less than the units digit.
Representation
:
x = units digit
Equation: 10 (x - 3) + x = 3 [(x – 3) + x] + 4
x - 3 = tens digit
Example #3: Find the original two-digit number. Its
tens digit is thrice the units digit. When digits are
reversed, the new number is 147 less than two times
the original number.
Representation
:
x = units digit
Equation: 10x + 3x = 2 [10 (3x) + x] -147
3x = tens digit
WORD PROBLEMS
INVOLVING EQUATIONS IN
ONE VARIABLE
(GEOMETRY PROBLEMS)
Example #1: The perimeter of a rectangle is 84 cm. Its
length is 12 cm longer than its width. Find the length?
Representation
:
x = width
Equation: P = 2L + 2W
x + 12 = length
P = 84 cm
84 = 2 (x + 12) +2x
Example #2: The perimeter of a rectangle is 72 cm. Its
width is 11 cm longer than its length. Find the width?
Representation
:
x = length
Equation: P = 2L + 2W
x + 11 = width
P = 72 cm
72 = 2 (x + 11) +2x
Example #3: One angle measures 30Âş less than two
times its supplement. Find the measure its
supplement.
Representation
:
x = supplement
Equation: x + 2x – 30º = 180º
2x - 30Âş = measure of the angle
Example #4: One angle measures 20Âş more than its
complement. Find the measure of the complement.
Representation
:
x = complement
Equation: x + (x + 20Âş) = 90Âş
x + 20Âş = measure of the angle
WORD PROBLEMS
INVOLVING EQUATIONS IN
ONE VARIABLE
(DISTANCE PROBLEMS)
Example #1: Two planes are 3 600 miles apart and fly
toward each other. Their rates differ by 90 miles per
hour. Find the rates if they will meet after 5 hours.
Representation
:
Rate
Plane A
5x + 5 (x + 90) = 3 600
Time Distance
Plane B
x 5 5x
x + 90 5 5 (x + 90)
Equation: D1 + D2 = DT
Example #2: Kerby spends 3 hours training. He runs at 8
miles per hour then he walks back to the starting point at 2
miles per hour. How long does he spend walking? How long
does he spend running?
Representation
:
Rate
Running
8x = 2 (3 – x)
Time Distance
Walking
8 x 8x
2 3 - x 2 (3 - x)
Equation: D1 = D2
Example #3: Bus A and Bus B started from one point and
travelled to opposite directions. Bus A travelled at 60 kph and
Bus B at 70 kph, how long will they be 650 km apart?
Representation
:
Rate
Bus A
60x + 70x = 650
Time Distance
Bus B
60 x 60x
70 x 70x
Equation: D1 + D2 = DT
WORD PROBLEMS
INVOLVING EQUATIONS IN
ONE VARIABLE
(MONEY PROBLEMS)
Example #1: A coin can has 5 peso and 1 peso coins. If
there are 12 more 5 peso coins than 1 peso coins, how
many of each kind are there in the coin can if the total
amount is 600 pesos?
Representation
:
x = 1 peso coins
Equation: x + 5 (x + 12) = 600
x + 12 = 5 peso coins
Example #2: Mr. Vite has 5 500 pesos in 100 peso bills
and 50 peso bills in his money box. He has 80 bills in
the money box. How many bills of each kind does he
have?
Representation
:
x = 50 peso bills
Equation: 50x + 100 (80 – x) = 5 500
80 - x = 100 peso bills
Example #3: Teacher Melvs got his salary in 1 000 peso
bills and 500 peso bills. The number of 1 000 peso bills
he got was 5 more than one-half the number of 500
peso bills. His salary is 25 000 pesos. How many bills
of each kind did he get?
Representation
:
x = 500 peso bills
Equation: 500x + 1 000 (
1
2
x + 5) = 25 000
1
2
x + 5 = 1 000 peso bills
WORD PROBLEMS
INVOLVING EQUATIONS IN
ONE VARIABLE
(SOLUTION/MIXTURE
PROBLEMS)
Example #1: How many gallons of solution with 30%
alcohol to be mixed with solutions with 40% alcohol to
obtain 50 gallons of solution with 35% alcohol?
Representation
: Number of
Gallons
Solution 1
Equation: .30x + .40 (50 – x) = .35 (50)
Percent of
Alcohol
Amount of
Alcohol
Solution 2
Solution 3
x
50 - x
50
30% = .30
40% = .40
35% = .35
.30x
.40 (50 – x)
.35 (50)
Example #2: How many kg of pili nuts at 75 pesos per
kg should I add to 30 kg of cashew nuts at 100 pesos
per kg if the mixture would costs 90 pesos per kg?
Representation
: Cost per
Kilogram
Pili Nuts
Equation: 75x + 100 (30) = 90 (25 + x)
Kilogram
Cashew
Nuts
Mixture
75
100
90
x
30
25 + x

Grade 7 Word Problems Involving Equations in One Variable PowerPoint Presentation

  • 1.
    WORD PROBLEMS INVOLVING EQUATIONSIN ONE VARIABLE (AGE PROBLEMS)
  • 2.
    Example #1: Viois now 24 years older than his brother. Find their present ages if he will be twice as old as his brother in 6 years. Representation : x = present age of Vio’s brother Present Future Vio brother x + 24 x (x + 24) + 6 x + 6 Equation: (x + 24) + 6 = 2 (x + 6)
  • 3.
    Example #2: Thesum of the ages of Kerby and his cousin is 42. How old is Kerby if he is 8 years younger than his cousin? Representation : x = present age of Kerby’s cousin Present Kerby cousin x - 8 x Equation: x + (x – 8) = 42
  • 4.
    Example #3: Sixyears ago, Eizen was 12 year younger than twice his sister’s age. How old is Eizen if he is thrice as old as his sister now. Representation : x = present age of Eizen’s sister Present Past Eizen sister 2x x 2x - 6 x - 6 Equation: 2x – 6 = 3 (x – 6) - 12
  • 5.
    WORD PROBLEMS INVOLVING EQUATIONSIN ONE VARIABLE (DIGIT PROBLEMS)
  • 6.
    Example #1: Findthe two-digit number if the sum of its digits is 8. The number is 11 times its units digit. Representation : x = units digit Equation: 10 (8 – x) + x = 11x 8 - x = tens digit
  • 7.
    Example #2: Thenumber is more than three times the sum of the digits. Find the two-digit number if the tens digit is less than the units digit. Representation : x = units digit Equation: 10 (x - 3) + x = 3 [(x – 3) + x] + 4 x - 3 = tens digit
  • 8.
    Example #3: Findthe original two-digit number. Its tens digit is thrice the units digit. When digits are reversed, the new number is 147 less than two times the original number. Representation : x = units digit Equation: 10x + 3x = 2 [10 (3x) + x] -147 3x = tens digit
  • 9.
    WORD PROBLEMS INVOLVING EQUATIONSIN ONE VARIABLE (GEOMETRY PROBLEMS)
  • 10.
    Example #1: Theperimeter of a rectangle is 84 cm. Its length is 12 cm longer than its width. Find the length? Representation : x = width Equation: P = 2L + 2W x + 12 = length P = 84 cm 84 = 2 (x + 12) +2x
  • 11.
    Example #2: Theperimeter of a rectangle is 72 cm. Its width is 11 cm longer than its length. Find the width? Representation : x = length Equation: P = 2L + 2W x + 11 = width P = 72 cm 72 = 2 (x + 11) +2x
  • 12.
    Example #3: Oneangle measures 30º less than two times its supplement. Find the measure its supplement. Representation : x = supplement Equation: x + 2x – 30º = 180º 2x - 30º = measure of the angle
  • 13.
    Example #4: Oneangle measures 20Âş more than its complement. Find the measure of the complement. Representation : x = complement Equation: x + (x + 20Âş) = 90Âş x + 20Âş = measure of the angle
  • 14.
    WORD PROBLEMS INVOLVING EQUATIONSIN ONE VARIABLE (DISTANCE PROBLEMS)
  • 15.
    Example #1: Twoplanes are 3 600 miles apart and fly toward each other. Their rates differ by 90 miles per hour. Find the rates if they will meet after 5 hours. Representation : Rate Plane A 5x + 5 (x + 90) = 3 600 Time Distance Plane B x 5 5x x + 90 5 5 (x + 90) Equation: D1 + D2 = DT
  • 16.
    Example #2: Kerbyspends 3 hours training. He runs at 8 miles per hour then he walks back to the starting point at 2 miles per hour. How long does he spend walking? How long does he spend running? Representation : Rate Running 8x = 2 (3 – x) Time Distance Walking 8 x 8x 2 3 - x 2 (3 - x) Equation: D1 = D2
  • 17.
    Example #3: BusA and Bus B started from one point and travelled to opposite directions. Bus A travelled at 60 kph and Bus B at 70 kph, how long will they be 650 km apart? Representation : Rate Bus A 60x + 70x = 650 Time Distance Bus B 60 x 60x 70 x 70x Equation: D1 + D2 = DT
  • 18.
    WORD PROBLEMS INVOLVING EQUATIONSIN ONE VARIABLE (MONEY PROBLEMS)
  • 19.
    Example #1: Acoin can has 5 peso and 1 peso coins. If there are 12 more 5 peso coins than 1 peso coins, how many of each kind are there in the coin can if the total amount is 600 pesos? Representation : x = 1 peso coins Equation: x + 5 (x + 12) = 600 x + 12 = 5 peso coins
  • 20.
    Example #2: Mr.Vite has 5 500 pesos in 100 peso bills and 50 peso bills in his money box. He has 80 bills in the money box. How many bills of each kind does he have? Representation : x = 50 peso bills Equation: 50x + 100 (80 – x) = 5 500 80 - x = 100 peso bills
  • 21.
    Example #3: TeacherMelvs got his salary in 1 000 peso bills and 500 peso bills. The number of 1 000 peso bills he got was 5 more than one-half the number of 500 peso bills. His salary is 25 000 pesos. How many bills of each kind did he get? Representation : x = 500 peso bills Equation: 500x + 1 000 ( 1 2 x + 5) = 25 000 1 2 x + 5 = 1 000 peso bills
  • 22.
    WORD PROBLEMS INVOLVING EQUATIONSIN ONE VARIABLE (SOLUTION/MIXTURE PROBLEMS)
  • 23.
    Example #1: Howmany gallons of solution with 30% alcohol to be mixed with solutions with 40% alcohol to obtain 50 gallons of solution with 35% alcohol? Representation : Number of Gallons Solution 1 Equation: .30x + .40 (50 – x) = .35 (50) Percent of Alcohol Amount of Alcohol Solution 2 Solution 3 x 50 - x 50 30% = .30 40% = .40 35% = .35 .30x .40 (50 – x) .35 (50)
  • 24.
    Example #2: Howmany kg of pili nuts at 75 pesos per kg should I add to 30 kg of cashew nuts at 100 pesos per kg if the mixture would costs 90 pesos per kg? Representation : Cost per Kilogram Pili Nuts Equation: 75x + 100 (30) = 90 (25 + x) Kilogram Cashew Nuts Mixture 75 100 90 x 30 25 + x