There was an equal number of boys and girls at the computer lab. After
49 of the boys and 42 girls left the computer lab, there were 10 more boys than girls at the computer lab. How many children were there at the computer lab at first?
| |
Boys |
Girls |
| Before |
9 u |
9 u |
| Change |
- 4 u |
- 42 |
| After |
5 u |
9 u - 42 |
Number of boys in the end
= 9 u - 4 u
= 5 u
If another 10 girls entered the computer lab, the number of boys and girls would be the same.
9 u - 42 + 10 = 5 u
9 u - 32 = 5 u
9 u - 5 u = 32
4 u = 32
1 u = 32 ÷ 4 = 8
Number of children in the computer lab at first
= 18 u
= 18 x 8
= 144
Answer(s): 144
