There are 143 children in a tuckshop.
38 of the boys and
47 of the girls wear spectacles, there are 77 children in the tuckshop who do not wear spectacles. How many girls do not wear spectacles?
| |
Boys |
Girls |
Total |
| Do not wear spectacles |
5 u |
3 p |
77 |
| Wear spectacles |
3 u |
4 p |
66 |
| Total |
8 u |
7 p |
143 |
Number of children who wear spectacles
= 143 - 77
= 66
5 u + 3 p = 77 --- (1)
3 u + 4 p = 66 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 231 --- (3)
(2)
x 5 15 u + 20 p = 330 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 330 - 231
20 p - 9 p = 99
11 p = 99
1 p = 99 ÷ 11 = 9
Number of girls who do not wear spectacles
= 3 p
= 3 x 9
= 27
Answer(s): 27
