There are 137 students in a basketball court.
38 of the boys and
47 of the girls wear spectacles, there are 76 students in the basketball court who do not wear spectacles. How many girls do not wear spectacles?
| |
Boys |
Girls |
Total |
| Do not wear spectacles |
5 u |
3 p |
76 |
| Wear spectacles |
3 u |
4 p |
61 |
| Total |
8 u |
7 p |
137 |
Number of students who wear spectacles
= 137 - 76
= 61
5 u + 3 p = 76 --- (1)
3 u + 4 p = 61 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 228 --- (3)
(2)
x 5 15 u + 20 p = 305 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 305 - 228
20 p - 9 p = 77
11 p = 77
1 p = 77 ÷ 11 = 7
Number of girls who do not wear spectacles
= 3 p
= 3 x 7
= 21
Answer(s): 21
