There are 122 children in a canteen.
27 of the boys and
35 of the girls wear glasses, there are 73 children in the canteen who do not wear glasses. How many girls do not wear glasses?
| |
Boys |
Girls |
Total |
| Do not wear glasses |
5 u |
2 p |
73 |
| Wear glasses |
2 u |
3 p |
49 |
| Total |
7 u |
5 p |
122 |
Number of children who wear glasses
= 122 - 73
= 49
5 u + 2 p = 73 --- (1)
2 u + 3 p = 49 --- (2)
Make u the same.
(1)
x 2 10 u + 4 p = 146 --- (3)
(2)
x 5 10 u + 15 p = 245 --- (4)
(4) - (3)
(10 u + 15 p) - (10 u + 4 p) = 245 - 146
15 p - 4 p = 99
11 p = 99
1 p = 99 ÷ 11 = 9
Number of girls who do not wear glasses
= 2 p
= 2 x 9
= 18
Answer(s): 18
