At a school, there were 30 boys from Club H and 30% more boys from Club J. Some boys from Club J left and the ratio of the number of boys from Club H to the number of boys from Club J became 5 : 3. How many boys from Club J left?
| |
Club H |
Club J |
| Before |
30 |
39 |
| Change |
|
- ? |
| After |
5 u |
3 u |
Number of boys from Club J at first in percent
= 100% + 30%
= 130%
Number of boys from Club J at first
= 130% x 30
=
130100 x 30
= 39
Number of boys in Club H remains unchanged.
5 u = 30
1 u = 30 ÷ 5 = 6
Number of boys from Club J in the end
= 3 u
= 3 x 6
= 18
Number of boys from Club J who left
= 39 - 18
= 21
Answer(s): 21
