There are 146 children in a school field.
38 of the girls and
47 of the boys wear glasses, there are 83 children in the school field who do not wear glasses. How many boys do not wear glasses?
| |
Girls |
Boys |
Total |
| Do not wear glasses |
5 u |
3 p |
83 |
| Wear glasses |
3 u |
4 p |
63 |
| Total |
8 u |
7 p |
146 |
Number of children who wear glasses
= 146 - 83
= 63
5 u + 3 p = 83 --- (1)
3 u + 4 p = 63 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 249 --- (3)
(2)
x 5 15 u + 20 p = 315 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 315 - 249
20 p - 9 p = 66
11 p = 66
1 p = 66 ÷ 11 = 6
Number of boys who do not wear glasses
= 3 p
= 3 x 6
= 18
Answer(s): 18
