There was an equal number of boys and girls at the canteen. After
35 of the boys and 41 girls left the canteen, there were 20 more boys than girls at the canteen. How many pupils were there at the canteen at first?
| |
Boys |
Girls |
| Before |
5 u |
5 u |
| Change |
- 3 u |
- 41 |
| After |
2 u |
5 u - 41 |
Number of boys in the end
= 5 u - 3 u
= 2 u
If another 20 girls entered the canteen, the number of boys and girls would be the same.
5 u - 41 + 20 = 2 u
5 u - 21 = 2 u
5 u - 2 u = 21
3 u = 21
1 u = 21 ÷ 3 = 7
Number of pupils in the canteen at first
= 10 u
= 10 x 7
= 70
Answer(s): 70
