Vaidev, Jack and Lee had some coins in the ratio of 3 : 4 : 7. Lee gave 50% of his coins to Vaidev and Jack. As a result, Vaidev had the same number of coins as Jack and Lee had 28 fewer coins than Vaidev.

1. What was the percentage increase in Vaidev's coins after receiving from Lee?
2. How many coins did Jack have at first?

Vaidev	Jack	Lee	Total
3 u	4 u	7 u	14 u
+ 3.5 u		- 3.5 u
5.25 u	5.25 u	3.5 u	14 u

(a)
Number of coins that Lee gave away
= 50% x 7
= ⁵⁰₁₀₀ x 7
= 3.5 u

Number of coins that Vaidev and Jack each had in the end
= (14 u - 3.5 u) ÷ 2
= 10.5 u ÷ 2
= 5.25 u

Increase in the number of coins that Vaidev had
= 5.25 u - 3 u
= 2.25 u

Percentage increase in Vaidev's coins after receiving from Lee
= ^2.25₃ x 100%
= 75%

(b)
5.25 u = 3.5 u + 28
5.25 u - 3.5 u = 28
1.75 u = 28

1 u = 28 ÷ 1.75 = 16

Number of coins that Jack had at first
= 4 u
= 4 x 16
= 64

Answer(s): (a) 75%; (b) 64