Owen, George and Glen had some stamps in the ratio of 6 : 7 : 13. Glen gave 50% of his stamps to Owen and George. As a result, Owen had the same number of stamps as George and Glen had 13 fewer stamps than Owen.

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

Owen	George	Glen	Total
6 u	7 u	13 u	26 u
+ 6.5 u		- 6.5 u
9.75 u	9.75 u	6.5 u	26 u

(a)
Number of stamps that Glen gave away
= 50% x 13
= ⁵⁰₁₀₀ x 13
= 6.5 u

Number of stamps that Owen and George each had in the end
= (26 u - 6.5 u) ÷ 2
= 19.5 u ÷ 2
= 9.75 u

Increase in the number of stamps that Owen had
= 9.75 u - 6 u
= 3.75 u

Percentage increase in Owen's stamps after receiving from Glen
= ^3.75₆ x 100%
= 62.5%

(b)
9.75 u = 6.5 u + 13
9.75 u - 6.5 u = 13
3.25 u = 13

1 u = 13 ÷ 3.25 = 4

Number of stamps that George had at first
= 7 u
= 7 x 4
= 28

Answer(s): (a) 62.5%; (b) 28