At a school, there were 10 children from Club R and 20% more children from Club S. Some children from Club S left and the ratio of the number of children from Club R to the number of children from Club S became 5 : 4. How many children from Club S left?
| |
Club R |
Club S |
| Before |
10 |
12 |
| Change |
|
- ? |
| After |
5 u |
4 u |
Number of children from Club S at first in percent
= 100% + 20%
= 120%
Number of children from Club S at first
= 120% x 10
=
120100 x 10
= 12
Number of children in Club R remains unchanged.
5 u = 10
1 u = 10 ÷ 5 = 2
Number of children from Club S in the end
= 4 u
= 4 x 2
= 8
Number of children from Club S who left
= 12 - 8
= 4
Answer(s): 4
