There are 145 pupils in a hall.
27 of the girls and
35 of the boys wear spectacles, there are 91 pupils in the hall who do not wear spectacles. How many boys do not wear spectacles?
| |
Girls |
Boys |
Total |
| Do not wear spectacles |
5 u |
2 p |
91 |
| Wear spectacles |
2 u |
3 p |
54 |
| Total |
7 u |
5 p |
145 |
Number of pupils who wear spectacles
= 145 - 91
= 54
5 u + 2 p = 91 --- (1)
2 u + 3 p = 54 --- (2)
Make u the same.
(1)
x 2 10 u + 4 p = 182 --- (3)
(2)
x 5 10 u + 15 p = 270 --- (4)
(4) - (3)
(10 u + 15 p) - (10 u + 4 p) = 270 - 182
15 p - 4 p = 88
11 p = 88
1 p = 88 ÷ 11 = 8
Number of boys who do not wear spectacles
= 2 p
= 2 x 8
= 16
Answer(s): 16
