Here are the steps to solve problems like these: 1. Identify the "is", "of", and "%" amounts given in the problem 2. Set up a proportion relating the amounts: is/of = %/100 3. Solve the proportion algebraically for the missing value Be sure to show the proportion and substitution steps to arrive at the solution. Drawing a percent bar can also help visualize the relationship between the amounts. Practice these types of problems until you feel comfortable setting up and solving the proportions. Let me know if any specific problems give you trouble.

1. Finding Percents of
numbers
Using the Is over Of technique
in conjunction with drawing
percent bars

2. What do you think is the answer??
• Find 25% of 20
• Let’s draw a picture.
? 25%
20 100%

3. Can you solve this as a proportion?
• Find 25% of 20
• What would the proportion look like?
x 25
? 25%
20 1 00
X=5
20 100%

4. We can do this Mathematically by
using a special proportion...just
find the following...
The Percent – it is the easiest to find.
Just look for the % sign!
The “Of” number - it is always just
behind the word of.
The “Is” number - it may or may not be
near the “is” word. If you find the
other two then what is left is the “is”!

5. Finding is, of or a Percent
is %
Use the proportion…
of 100
Find the missing number by drawing a bar and using the
proportion.
a) 15% of 900 is what?
x 15 ? 15%
900 1 00
x = 135
900 100

6. Finding is, of or a Percent
is %
of 100
Find the missing number by drawing a bar and using the
proportion.
b) What % of 84 is 63?
63 %
84 1 00
63 x%
X = 75% 84 100

7. Finding is, of or a Percent
is %
of 100
Find the missing number by drawing a bar and
using the proportion.
c) 35% of what # is 7?
7 35%
7 35
x 1 00
? 100
X = 20

8. Finding is, of or a Percent
is %
of 100
Find the missing number by drawing a bar
and using the proportion.
d) 2.5% of 120 is what?
? 2.5%
x 2.5
1 20 1 00
x=3 120 100

9. Finding is, of or a Percent
is %
of 100
Find the missing number by drawing a bar
and using the proportion.
60% of 600 is what number?
x 60
600 1 00 x 60%
x = 360 600 100

10. Homework: P. 322 #2-26 evens
You MUST show the proportion and the
work you do to get the answer.