There are 161 students in a tuckshop.
27 of the girls and
35 of the boys wear watches, there are 104 students in the tuckshop who do not wear watches. How many boys wear watches?
| |
Girls |
Boys |
Total |
| Do not wear watches |
5 u |
2 p |
104 |
| Wear watches |
2 u |
3 p |
57 |
| Total |
7 u |
5 p |
161 |
Number of students who wear watches
= 161 - 104
= 57
5 u + 2 p = 104 --- (1)
2 u + 3 p = 57 --- (2)
Make u the same.
(1)
x 2 10 u + 4 p = 208 --- (3)
(2)
x 5 10 u + 15 p = 285 --- (4)
(4) - (3)
(10 u + 15 p) - (10 u + 4 p) = 285 - 208
15 p - 4 p = 77
11 p = 77
1 p = 77 ÷ 11 = 7
Number of boys who wear watches
= 3 p
= 3 x 7
= 21
Answer(s): 21
