There was an equal number of girls and boys at the classroom. After
57 of the girls and 32 boys left the classroom, there were 17 more girls than boys at the classroom. How many pupils were there at the classroom at first?
| |
Girls |
Boys |
| Before |
7 u |
7 u |
| Change |
- 5 u |
- 32 |
| After |
2 u |
7 u - 32 |
Number of girls in the end
= 7 u - 5 u
= 2 u
If another 17 boys entered the classroom, the number of girls and boys would be the same.
7 u - 32 + 17 = 2 u
7 u - 15 = 2 u
7 u - 2 u = 15
5 u = 15
1 u = 15 ÷ 5 = 3
Number of pupils in the classroom at first
= 14 u
= 14 x 3
= 42
Answer(s): 42
