There was an equal number of girls and boys at the school hall. After
59 of the girls and 35 boys left the school hall, there were 20 more girls than boys at the school hall. How many children were there at the school hall at first?
| |
Girls |
Boys |
| Before |
9 u |
9 u |
| Change |
- 5 u |
- 35 |
| After |
4 u |
9 u - 35 |
Number of girls in the end
= 9 u - 5 u
= 4 u
If another 20 boys entered the school hall, the number of girls and boys would be the same.
9 u - 35 + 20 = 4 u
9 u - 15 = 4 u
9 u - 4 u = 15
5 u = 15
1 u = 15 ÷ 5 = 3
Number of children in the school hall at first
= 18 u
= 18 x 3
= 54
Answer(s): 54
