There are 145 children in a basketball court.
38 of the girls and
47 of the boys wear glasses, there are 81 children in the basketball court who do not wear glasses. How many boys wear glasses?
| |
Girls |
Boys |
Total |
| Do not wear glasses |
5 u |
3 p |
81 |
| Wear glasses |
3 u |
4 p |
64 |
| Total |
8 u |
7 p |
145 |
Number of children who wear glasses
= 145 - 81
= 64
5 u + 3 p = 81 --- (1)
3 u + 4 p = 64 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 243 --- (3)
(2)
x 5 15 u + 20 p = 320 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 320 - 243
20 p - 9 p = 77
11 p = 77
1 p = 77 ÷ 11 = 7
Number of boys who wear glasses
= 4 p
= 4 x 7
= 28
Answer(s): 28
