There was an equal number of boys and girls at the classroom. After
25 of the boys and 51 girls left the classroom, there were 25 more boys than girls at the classroom. How many students were there at the classroom at first?
| |
Boys |
Girls |
| Before |
5 u |
5 u |
| Change |
- 2 u |
- 51 |
| After |
3 u |
5 u - 51 |
Number of boys in the end
= 5 u - 2 u
= 3 u
If another 25 girls entered the classroom, the number of boys and girls would be the same.
5 u - 51 + 25 = 3 u
5 u - 26 = 3 u
5 u - 3 u = 26
2 u = 26
1 u = 26 ÷ 2 = 13
Number of students in the classroom at first
= 10 u
= 10 x 13
= 130
Answer(s): 130
