At a school, there were 30 boys from Club C and 40% more boys from Club D. Some boys from Club D left and the ratio of the number of boys from Club C to the number of boys from Club D became 6 : 5. How many boys from Club D left?
| |
Club C |
Club D |
| Before |
30 |
42 |
| Change |
|
- ? |
| After |
6 u |
5 u |
Number of boys from Club D at first in percent
= 100% + 40%
= 140%
Number of boys from Club D at first
= 140% x 30
=
140100 x 30
= 42
Number of boys in Club C remains unchanged.
6 u = 30
1 u = 30 ÷ 6 = 5
Number of boys from Club D in the end
= 5 u
= 5 x 5
= 25
Number of boys from Club D who left
= 42 - 25
= 17
Answer(s): 17
