Riordan, George and Harry had some stamps in the ratio of 2 : 3 : 5. Harry gave 40% of his stamps to Riordan and George. As a result, Riordan had the same number of stamps as George and Harry had 10 fewer stamps than Riordan.

1. What was the percentage increase in Riordan's stamps after receiving from Harry?
2. How many stamps did George have at first?

Riordan	George	Harry	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 Harry gave away
= 40% x 5
= ⁴⁰₁₀₀ x 5
= 2 u

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

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

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

(b)
3.5 u = 3 u + 10
3.5 u - 3 u = 10
0.5 u = 10

1 u = 10 ÷ 0.5 = 20

Number of stamps that George had at first
= 3 u
= 3 x 20
= 60

Answer(s): (a) 75%; (b) 60