There are 193 pupils in a canteen.
38 of the boys and
47 of the girls wear spectacles, there are 111 pupils in the canteen who do not wear spectacles. How many girls wear spectacles?
| |
Boys |
Girls |
Total |
| Do not wear spectacles |
5 u |
3 p |
111 |
| Wear spectacles |
3 u |
4 p |
82 |
| Total |
8 u |
7 p |
193 |
Number of pupils who wear spectacles
= 193 - 111
= 82
5 u + 3 p = 111 --- (1)
3 u + 4 p = 82 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 333 --- (3)
(2)
x 5 15 u + 20 p = 410 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 410 - 333
20 p - 9 p = 77
11 p = 77
1 p = 77 ÷ 11 = 7
Number of girls who wear spectacles
= 4 p
= 4 x 7
= 28
Answer(s): 28
