There was an equal number of boys and girls at the classroom. After
59 of the boys and 45 girls left the classroom, there were 20 more boys than girls at the classroom. How many students were there at the classroom at first?
| |
Boys |
Girls |
| Before |
9 u |
9 u |
| Change |
- 5 u |
- 45 |
| After |
4 u |
9 u - 45 |
Number of boys in the end
= 9 u - 5 u
= 4 u
If another 20 girls entered the classroom, the number of boys and girls would be the same.
9 u - 45 + 20 = 4 u
9 u - 25 = 4 u
9 u - 4 u = 25
5 u = 25
1 u = 25 ÷ 5 = 5
Number of students in the classroom at first
= 18 u
= 18 x 5
= 90
Answer(s): 90
