At a school, there were 30 students from Club C and 10% more students from Club D. Some students from Club D left and the ratio of the number of students from Club C to the number of students from Club D became 5 : 2. How many students from Club D left?
| |
Club C |
Club D |
| Before |
30 |
33 |
| Change |
|
- ? |
| After |
5 u |
2 u |
Number of students from Club D at first in percent
= 100% + 10%
= 110%
Number of students from Club D at first
= 110% x 30
=
110100 x 30
= 33
Number of students in Club C remains unchanged.
5 u = 30
1 u = 30 ÷ 5 = 6
Number of students from Club D in the end
= 2 u
= 2 x 6
= 12
Number of students from Club D who left
= 33 - 12
= 21
Answer(s): 21
