Systems of linear 
equations 
By Comenius group of PGU, Germany
Some tasks 
Here we have some tasks for solving 
systems of linear equations. 
We hope that it’s a help for the next class 
test or other things. Some tasks haven’t got 
solutions but we hope that isn’t a problem. 
Comenius group from Germany
bakery 
Yesterday I bought at the bakery three 
breads and 5 rolls for 4,10 euros. Today I 
bought 5 breads and 2 rolls for 5,80 euros. 
O How expensive is one bread and one 
roll?
Solution: 
bakery 
Bread x 
Roll y 
3x+5y= 4,10 
5x+2y= 5,80 
3x+5y= 4,10 /-5y 
3x= 4,10-5y /:3 
x = 1,37-1,67y 
5x+2y= 5,80 /T 
6,85-8,35y+2y= 5,80 /T 
6,85-6,35y= 5,80 /-6,85 
-6,85y= -1,05 /:6,85 
-y=-0,153 /*(-1) 
y=ca. 0,153 euro 
3x+5y=4,10 /T 
3x+0,765=4,10 /-0,765 
3x=3,34 /:3 
x= ca. 1,11 euro
Icehockey in Belarus 
It’s icehockey worldchampionschip in Belarus. To the 
first game, which was Germany against Russia, 2340 
adults and 780 children came. The organisators 
earned 50700€. The return match was watched by 
2520 adults and 360 children. In that game they 
earned 51480€. 
O How much does an entrance ticket cost for an 
adult and how much does a child have to pay? 
O How many children were visiting the game (in 
percent)?
Solution: 
Icehockey in Belarus 
a)2340x + 780y = 50700 |-2340x 
780y = 50700 – 2340x |:780 
y = 65 – 3x 
2520x + 360y = 51480 |-2520x 
360y = 51480 – 2520x |:360 
y = 143 – 7x 
65 – 3x = 143 – 7x |+7x 
65 + 4x = 143 |+65 
4x = 78 |:4 
x = 19,5 
y = 6,5 
Answer: An adult have to pay 19,5€ and a child have to pay 6,5€. 
b)First game: 
2340 + 780 = 3120 
3120 = 100 % 
31,2 = 1 % 
780 : 31,2 = 25 % 
Second game: 
2520 + 360 = 2880 
2880 = 100% 
28,8 = 1% 
360 : 28,8 = 12,5%
The illegal Pokémon market 
On the illegal market for Pokémon, a seller 
sells only Charmanders and Charizards. 
He sells 5 Charmanders and 8 Charizards 
on one day. He gets 2525$ in total. The day 
before he sold 12 Charmanders and 4 
Charizards, so he earned 1500$. 
O How much costs one of each 
Pokémon?
A handball club 
A handball club has two games. To the first 
game came 1346 adult and 634 children. 
They took 11324 euro for tickets of this 
game. To the next game 2359 adults 
cameand only the half of the children, who 
came to the first game. They took 5.235.572 
Euro from tickets. 
O How much costs a ticket for an adult 
and how much for a child?

Linear equations1

  • 1.
    Systems of linear equations By Comenius group of PGU, Germany
  • 2.
    Some tasks Herewe have some tasks for solving systems of linear equations. We hope that it’s a help for the next class test or other things. Some tasks haven’t got solutions but we hope that isn’t a problem. Comenius group from Germany
  • 3.
    bakery Yesterday Ibought at the bakery three breads and 5 rolls for 4,10 euros. Today I bought 5 breads and 2 rolls for 5,80 euros. O How expensive is one bread and one roll?
  • 4.
    Solution: bakery Breadx Roll y 3x+5y= 4,10 5x+2y= 5,80 3x+5y= 4,10 /-5y 3x= 4,10-5y /:3 x = 1,37-1,67y 5x+2y= 5,80 /T 6,85-8,35y+2y= 5,80 /T 6,85-6,35y= 5,80 /-6,85 -6,85y= -1,05 /:6,85 -y=-0,153 /*(-1) y=ca. 0,153 euro 3x+5y=4,10 /T 3x+0,765=4,10 /-0,765 3x=3,34 /:3 x= ca. 1,11 euro
  • 5.
    Icehockey in Belarus It’s icehockey worldchampionschip in Belarus. To the first game, which was Germany against Russia, 2340 adults and 780 children came. The organisators earned 50700€. The return match was watched by 2520 adults and 360 children. In that game they earned 51480€. O How much does an entrance ticket cost for an adult and how much does a child have to pay? O How many children were visiting the game (in percent)?
  • 6.
    Solution: Icehockey inBelarus a)2340x + 780y = 50700 |-2340x 780y = 50700 – 2340x |:780 y = 65 – 3x 2520x + 360y = 51480 |-2520x 360y = 51480 – 2520x |:360 y = 143 – 7x 65 – 3x = 143 – 7x |+7x 65 + 4x = 143 |+65 4x = 78 |:4 x = 19,5 y = 6,5 Answer: An adult have to pay 19,5€ and a child have to pay 6,5€. b)First game: 2340 + 780 = 3120 3120 = 100 % 31,2 = 1 % 780 : 31,2 = 25 % Second game: 2520 + 360 = 2880 2880 = 100% 28,8 = 1% 360 : 28,8 = 12,5%
  • 7.
    The illegal Pokémonmarket On the illegal market for Pokémon, a seller sells only Charmanders and Charizards. He sells 5 Charmanders and 8 Charizards on one day. He gets 2525$ in total. The day before he sold 12 Charmanders and 4 Charizards, so he earned 1500$. O How much costs one of each Pokémon?
  • 8.
    A handball club A handball club has two games. To the first game came 1346 adult and 634 children. They took 11324 euro for tickets of this game. To the next game 2359 adults cameand only the half of the children, who came to the first game. They took 5.235.572 Euro from tickets. O How much costs a ticket for an adult and how much for a child?