Oliver, Brandon and Bobby had some coins in the ratio of 3 : 4 : 7. Bobby gave 40% of his coins to Oliver and Brandon. As a result, Oliver had the same number of coins as Brandon and Bobby had 14 fewer coins than Oliver.

1. What was the percentage increase in Oliver's coins after receiving from Bobby?
2. How many coins did Brandon have at first?

Oliver	Brandon	Bobby	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 coins that Bobby gave away
= 40% x 7
= ⁴⁰₁₀₀ x 7
= 2.8 u

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

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

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

(b)
4.9 u = 4.2 u + 14
4.9 u - 4.2 u = 14
0.7 u = 14

1 u = 14 ÷ 0.7 = 20

Number of coins that Brandon had at first
= 4 u
= 4 x 20
= 80

Answer(s): (a) 63.333333333333%; (b) 80