Brandon, Billy and Will had some stamps in the ratio of 2 : 3 : 5. Will gave 40% of his stamps to Brandon and Billy. As a result, Brandon had the same number of stamps as Billy and Will had 17 fewer stamps than Brandon.

1. What was the percentage increase in Brandon's stamps after receiving from Will?
2. How many stamps did Billy have at first?

Brandon	Billy	Will	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 Will gave away
= 40% x 5
= ⁴⁰₁₀₀ x 5
= 2 u

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

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

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

(b)
3.5 u = 3 u + 17
3.5 u - 3 u = 17
0.5 u = 17

1 u = 17 ÷ 0.5 = 34

Number of stamps that Billy had at first
= 3 u
= 3 x 34
= 102

Answer(s): (a) 75%; (b) 102