Oliver, Archie and David had some stickers in the ratio of 3 : 4 : 7. David gave 40% of his stickers to Oliver and Archie. As a result, Oliver had the same number of stickers as Archie and David had 28 fewer stickers than Oliver.

1. What was the percentage increase in Oliver's stickers after receiving from David?
2. How many stickers did Archie have at first?

Oliver	Archie	David	Total
3 u	4 u	7 u	14 u
+ 2.8 u		- 2.8 u
4.9 u	4.9 u	4.2 u	14 u

(a)
Number of stickers that David gave away
= 40% x 7
= ⁴⁰₁₀₀ x 7
= 2.8 u

Number of stickers that Oliver and Archie each had in the end
= (14 u - 4.2 u) ÷ 2
= 9.8 u ÷ 2
= 4.9 u

Increase in the number of stickers that Oliver had
= 4.9 u - 3 u
= 1.9 u

Percentage increase in Oliver's stickers after receiving from David
= ^1.9₃ x 100%
= 63.333333333333%

(b)
4.9 u = 4.2 u + 28
4.9 u - 4.2 u = 28
0.7 u = 28

1 u = 28 ÷ 0.7 = 40

Number of stickers that Archie had at first
= 4 u
= 4 x 40
= 160

Answer(s): (a) 63.333333333333%; (b) 160