Ivan, Charlie and Tommy had some stamps in the ratio of 2 : 3 : 5. Tommy gave 40% of his stamps to Ivan and Charlie. As a result, Ivan had the same number of stamps as Charlie and Tommy had 20 fewer stamps than Ivan.

1. What was the percentage increase in Ivan's stamps after receiving from Tommy?
2. How many stamps did Charlie have at first?

Ivan	Charlie	Tommy	Total
2 u	3 u	5 u	10 u
+ 2 u		- 2 u
3.5 u	3.5 u	3 u	10 u

(a)
Number of stamps that Tommy gave away
= 40% x 5
= ⁴⁰₁₀₀ x 5
= 2 u

Number of stamps that Ivan and Charlie each had in the end
= (10 u - 3 u) ÷ 2
= 7 u ÷ 2
= 3.5 u

Increase in the number of stamps that Ivan had
= 3.5 u - 2 u
= 1.5 u

Percentage increase in Ivan's stamps after receiving from Tommy
= ^1.5₂ x 100%
= 75%

(b)
3.5 u = 3 u + 20
3.5 u - 3 u = 20
0.5 u = 20

1 u = 20 ÷ 0.5 = 40

Number of stamps that Charlie had at first
= 3 u
= 3 x 40
= 120

Answer(s): (a) 75%; (b) 120