There are 122 pupils in a tuckshop.
38 of the boys and
47 of the girls wear watches, there are 68 pupils in the tuckshop who do not wear watches. How many girls wear watches?
| |
Boys |
Girls |
Total |
| Do not wear watches |
5 u |
3 p |
68 |
| Wear watches |
3 u |
4 p |
54 |
| Total |
8 u |
7 p |
122 |
Number of pupils who wear watches
= 122 - 68
= 54
5 u + 3 p = 68 --- (1)
3 u + 4 p = 54 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 204 --- (3)
(2)
x 5 15 u + 20 p = 270 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 270 - 204
20 p - 9 p = 66
11 p = 66
1 p = 66 ÷ 11 = 6
Number of girls who wear watches
= 4 p
= 4 x 6
= 24
Answer(s): 24
