There was an equal number of girls and boys at the classroom. After
29 of the girls and 30 boys left the classroom, there were 16 more girls than boys at the classroom. How many pupils were there at the classroom at first?
|
Girls |
Boys |
Before |
9 u |
9 u |
Change |
- 2 u |
- 30 |
After |
7 u |
9 u - 30 |
Number of girls in the end
= 9 u - 2 u
= 7 u
If another 16 boys entered the classroom, the number of girls and boys would be the same.
9 u - 30 + 16 = 7 u
9 u - 14 = 7 u
9 u - 7 u = 14
2 u = 14
1 u = 14 ÷ 2 = 7
Number of pupils in the classroom at first
= 18 u
= 18 x 7
= 126
Answer(s): 126