There are 144 pupils in a parade square.
38 of the girls and
47 of the boys wear spectacles, there are 79 pupils in the parade square who do not wear spectacles. How many boys wear spectacles?
| |
Girls |
Boys |
Total |
| Do not wear spectacles |
5 u |
3 p |
79 |
| Wear spectacles |
3 u |
4 p |
65 |
| Total |
8 u |
7 p |
144 |
Number of pupils who wear spectacles
= 144 - 79
= 65
5 u + 3 p = 79 --- (1)
3 u + 4 p = 65 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 237 --- (3)
(2)
x 5 15 u + 20 p = 325 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 325 - 237
20 p - 9 p = 88
11 p = 88
1 p = 88 ÷ 11 = 8
Number of boys who wear spectacles
= 4 p
= 4 x 8
= 32
Answer(s): 32
