At a concert hall, there were
37 as many adults as children at first. After 40 adults left, there were 120 more children than adults remaining at a concert hall. How many adults were at the concert hall at first?
| |
Adults |
Children |
| Before |
3 u |
7 u |
| Change |
- 40 |
|
| After |
3 u - 40 |
7 u |
In the end, the number of children was 120 more than the number of adults. If another 120 adults entered the concert hall, the number of children and adults would be the same.
7 u = 3 u - 40 + 120
7 u - 3 u = 120 - 40
4 u = 80
1 u = 80 ÷ 4 = 20
Number of adults at first
= 3 u
= 3 x 20
= 60
Answer: 60
