There are 90 students in a canteen.
27 of the boys and
35 of the girls wear watches, there are 58 students in the canteen who do not wear watches. How many girls wear watches?
| |
Boys |
Girls |
Total |
| Do not wear watches |
5 u |
2 p |
58 |
| Wear watches |
2 u |
3 p |
32 |
| Total |
7 u |
5 p |
90 |
Number of students who wear watches
= 90 - 58
= 32
5 u + 2 p = 58 --- (1)
2 u + 3 p = 32 --- (2)
Make u the same.
(1)
x 2 10 u + 4 p = 116 --- (3)
(2)
x 5 10 u + 15 p = 160 --- (4)
(4) - (3)
(10 u + 15 p) - (10 u + 4 p) = 160 - 116
15 p - 4 p = 44
11 p = 44
1 p = 44 ÷ 11 = 4
Number of girls who wear watches
= 3 p
= 3 x 4
= 12
Answer(s): 12
