Glen, Sean and Vincent had some stamps in the ratio of 4 : 5 : 9. Vincent gave 40% of his stamps to Glen and Sean. As a result, Glen had the same number of stamps as Sean and Vincent had 27 fewer stamps than Glen.

1. What was the percentage increase in Glen's stamps after receiving from Vincent?
2. How many stamps did Sean have at first?

Glen	Sean	Vincent	Total
4 u	5 u	9 u	18 u
+ 3.6 u		- 3.6 u
6.3 u	6.3 u	5.4 u	18 u

(a)
Number of stamps that Vincent gave away
= 40% x 9
= ⁴⁰₁₀₀ x 9
= 3.6 u

Number of stamps that Glen and Sean each had in the end
= (18 u - 5.4 u) ÷ 2
= 12.6 u ÷ 2
= 6.3 u

Increase in the number of stamps that Glen had
= 6.3 u - 4 u
= 2.3 u

Percentage increase in Glen's stamps after receiving from Vincent
= ^2.3₄ x 100%
= 57.5%

(b)
6.3 u = 5.4 u + 27
6.3 u - 5.4 u = 27
0.9 u = 27

1 u = 27 ÷ 0.9 = 30

Number of stamps that Sean had at first
= 5 u
= 5 x 30
= 150

Answer(s): (a) 57.5%; (b) 150