At a school, there were 40 boys from Club R and 30% less boys from Club S. Some boys joined Club S and the ratio of the number of boys from Club R to the number of boys from Club S became 5 : 4. How many boys joined Club S?
| |
Club R |
Club S |
| Before |
40 |
28 |
| Change |
|
+ ? |
| After |
5 u |
4 u |
Number of boys from Club S at first in percent
= 100% - 30%
= 70%
Number of boys from Club S at first
= 70% x 40
=
70100 x 40
= 28
Number of boys in Club R remains unchanged.
5 u = 40
1 u = 40 ÷ 5 = 8
Number of boys from Club S in the end
= 4 u
= 4 x 8
= 32
Number of boys joined Club S
= 32 - 28
= 4
Answer(s): 4
