There was an equal number of girls and boys at the computer lab. After
49 of the girls and 59 boys left the computer lab, there were 19 more girls than boys at the computer lab. How many children were there at the computer lab at first?
| |
Girls |
Boys |
| Before |
9 u |
9 u |
| Change |
- 4 u |
- 59 |
| After |
5 u |
9 u - 59 |
Number of girls in the end
= 9 u - 4 u
= 5 u
If another 19 boys entered the computer lab, the number of girls and boys would be the same.
9 u - 59 + 19 = 5 u
9 u - 40 = 5 u
9 u - 5 u = 40
4 u = 40
1 u = 40 ÷ 4 = 10
Number of children in the computer lab at first
= 18 u
= 18 x 10
= 180
Answer(s): 180
