There was an equal number of girls and boys at the computer lab. After
35 of the girls and 57 boys left the computer lab, there were 12 more girls than boys at the computer lab. How many pupils were there at the computer lab at first?
| |
Girls |
Boys |
| Before |
5 u |
5 u |
| Change |
- 3 u |
- 57 |
| After |
2 u |
5 u - 57 |
Number of girls in the end
= 5 u - 3 u
= 2 u
If another 12 boys entered the computer lab, the number of girls and boys would be the same.
5 u - 57 + 12 = 2 u
5 u - 45 = 2 u
5 u - 2 u = 45
3 u = 45
1 u = 45 ÷ 3 = 15
Number of pupils in the computer lab at first
= 10 u
= 10 x 15
= 150
Answer(s): 150
