At a school, there were 30 children from Club C and 40% more children from Club D. Some children from Club D left and the ratio of the number of children from Club C to the number of children from Club D became 5 : 2. How many children from Club D left?
| |
Club C |
Club D |
| Before |
30 |
42 |
| Change |
|
- ? |
| After |
5 u |
2 u |
Number of children from Club D at first in percent
= 100% + 40%
= 140%
Number of children from Club D at first
= 140% x 30
=
140100 x 30
= 42
Number of children in Club C remains unchanged.
5 u = 30
1 u = 30 ÷ 5 = 6
Number of children from Club D in the end
= 2 u
= 2 x 6
= 12
Number of children from Club D who left
= 42 - 12
= 30
Answer(s): 30
