There are 193 students in a tuckshop.
38 of the girls and
47 of the boys wear glasses, there are 111 students in the tuckshop who do not wear glasses. How many boys do not wear glasses?
| |
Girls |
Boys |
Total |
| Do not wear glasses |
5 u |
3 p |
111 |
| Wear glasses |
3 u |
4 p |
82 |
| Total |
8 u |
7 p |
193 |
Number of students who wear glasses
= 193 - 111
= 82
5 u + 3 p = 111 --- (1)
3 u + 4 p = 82 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 333 --- (3)
(2)
x 5 15 u + 20 p = 410 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 410 - 333
20 p - 9 p = 77
11 p = 77
1 p = 77 ÷ 11 = 7
Number of boys who do not wear glasses
= 3 p
= 3 x 7
= 21
Answer(s): 21
