There was an equal number of boys and girls at the music room. After
35 of the boys and 33 girls left the music room, there were 21 more boys than girls at the music room. How many children were there at the music room at first?
| |
Boys |
Girls |
| Before |
5 u |
5 u |
| Change |
- 3 u |
- 33 |
| After |
2 u |
5 u - 33 |
Number of boys in the end
= 5 u - 3 u
= 2 u
If another 21 girls entered the music room, the number of boys and girls would be the same.
5 u - 33 + 21 = 2 u
5 u - 12 = 2 u
5 u - 2 u = 12
3 u = 12
1 u = 12 ÷ 3 = 4
Number of children in the music room at first
= 10 u
= 10 x 4
= 40
Answer(s): 40
