There was an equal number of boys and girls at the auditorium. After
37 of the boys and 50 girls left the auditorium, there were 20 more boys than girls at the auditorium. How many pupils were there at the auditorium at first?
| |
Boys |
Girls |
| Before |
7 u |
7 u |
| Change |
- 3 u |
- 50 |
| After |
4 u |
7 u - 50 |
Number of boys in the end
= 7 u - 3 u
= 4 u
If another 20 girls entered the auditorium, the number of boys and girls would be the same.
7 u - 50 + 20 = 4 u
7 u - 30 = 4 u
7 u - 4 u = 30
3 u = 30
1 u = 30 ÷ 3 = 10
Number of pupils in the auditorium at first
= 14 u
= 14 x 10
= 140
Answer(s): 140
