Mr Andy bought some pizzas for a group of pupils. There was an equal number of girls and boys. The girls received 2 times as many pizzas as the boys. Each boy ate
15 of a pizza and the boys finished all the pizzas given to them. Each girl ate
110 of a pizza and the girls had 13
12 pizzas left. How many pizzas did Mr Andy buy?
|
Girls (1) |
Boys (2) |
Before |
2 u |
1 u |
Change |
- 1 p |
- 2 p |
After |
135 |
0 |
15 =
210 Cutting the slices of pizzas into same size. Each pizza was cut into 10 slices. Every girl ate 1 slice of pizza and every boy ate 2 slices of pizza.
Number of slices that the girls had left
= 13
12 ÷
110 =
272 x 10
= 135
2 u - 1 p = 135 --- (1)
1 u - 2 p = 0
1 u = 2 p --- (2)
Make u the same.
(2)
x22 u = 4 p --- (3)
Substitute (3) into (1).
2 u - 1 p = 135
4 p - 1 p = 135
3 p = 135
1 p = 135 ÷ 3 = 45
Total number of slices of pizzas for girls
= 135 + 1 p
= 135 + 45
= 180
Total number of slices of pizzas for boys
= 180 ÷ 2
= 90
Total number of slices of pizzas for pupils
= 180 + 90
= 270
Total number of pizzas that Mr Andy bought
= 270 ÷ 10
= 27
Answer(s): 27