There are 141 pupils in a canteen.
27 of the girls and
35 of the boys wear glasses, there are 96 pupils in the canteen who do not wear glasses. How many boys do not wear glasses?
| |
Girls |
Boys |
Total |
| Do not wear glasses |
5 u |
2 p |
96 |
| Wear glasses |
2 u |
3 p |
45 |
| Total |
7 u |
5 p |
141 |
Number of pupils who wear glasses
= 141 - 96
= 45
5 u + 2 p = 96 --- (1)
2 u + 3 p = 45 --- (2)
Make u the same.
(1)
x 2 10 u + 4 p = 192 --- (3)
(2)
x 5 10 u + 15 p = 225 --- (4)
(4) - (3)
(10 u + 15 p) - (10 u + 4 p) = 225 - 192
15 p - 4 p = 33
11 p = 33
1 p = 33 ÷ 11 = 3
Number of boys who do not wear glasses
= 2 p
= 2 x 3
= 6
Answer(s): 6
