There are 136 pupils in a school field.
38 of the girls and
47 of the boys wear glasses, there are 74 pupils in the school field who do not wear glasses. How many boys wear glasses?
| |
Girls |
Boys |
Total |
| Do not wear glasses |
5 u |
3 p |
74 |
| Wear glasses |
3 u |
4 p |
62 |
| Total |
8 u |
7 p |
136 |
Number of pupils who wear glasses
= 136 - 74
= 62
5 u + 3 p = 74 --- (1)
3 u + 4 p = 62 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 222 --- (3)
(2)
x 5 15 u + 20 p = 310 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 310 - 222
20 p - 9 p = 88
11 p = 88
1 p = 88 ÷ 11 = 8
Number of boys who wear glasses
= 4 p
= 4 x 8
= 32
Answer(s): 32
