There are 142 children in a school field.
27 of the girls and
35 of the boys wear watches, there are 92 children in the school field who do not wear watches. How many boys do not wear watches?
| |
Girls |
Boys |
Total |
| Do not wear watches |
5 u |
2 p |
92 |
| Wear watches |
2 u |
3 p |
50 |
| Total |
7 u |
5 p |
142 |
Number of children who wear watches
= 142 - 92
= 50
5 u + 2 p = 92 --- (1)
2 u + 3 p = 50 --- (2)
Make u the same.
(1)
x 2 10 u + 4 p = 184 --- (3)
(2)
x 5 10 u + 15 p = 250 --- (4)
(4) - (3)
(10 u + 15 p) - (10 u + 4 p) = 250 - 184
15 p - 4 p = 66
11 p = 66
1 p = 66 ÷ 11 = 6
Number of boys who do not wear watches
= 2 p
= 2 x 6
= 12
Answer(s): 12
