There are 133 children in a school field.
38 of the boys and
47 of the girls wear glasses, there are 79 children in the school field who do not wear glasses. How many girls do not wear glasses?
| |
Boys |
Girls |
Total |
| Do not wear glasses |
5 u |
3 p |
79 |
| Wear glasses |
3 u |
4 p |
54 |
| Total |
8 u |
7 p |
133 |
Number of children who wear glasses
= 133 - 79
= 54
5 u + 3 p = 79 --- (1)
3 u + 4 p = 54 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 237 --- (3)
(2)
x 5 15 u + 20 p = 270 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 270 - 237
20 p - 9 p = 33
11 p = 33
1 p = 33 ÷ 11 = 3
Number of girls who do not wear glasses
= 3 p
= 3 x 3
= 9
Answer(s): 9
