Gem and Xandra collected stamps. Gem gave 60% of her stamps to Xandra and as a result, Xandra's stamps increased by 20%. If Gem had 20 stamps left, find the number of stamps Xandra should give to Gem in the end so that both had an equal number of stamps.

	Gem	Xandra	Comparing the change in Xandra's stamps
Before	5x1 = 5 u		5x3 = 15u
Change	- 3x1 = - 3 u	+ 3x1 = + 3 u	+ 1x3 = + 3 u
After	2x1 = 2 u		6x3 = 18 u

60% = ⁶⁰₁₀₀ = ³₅
20% = ²⁰₁₀₀ = ¹₅

The increase in the number of stamps that Xandra had is repeated.  Make the increase in the number of stamps that Xandra had the same. LCM of 3 and 1 = 3

2 u = 20

1 u = 20 ÷ 2 = 10

Number of stamps that Xandra had more than Gem in the end
= 18 u - 2 u
= 16 u

Number of stamps that Xandra should give to Gem so that both had an equal number of stamps in the end
= 16 u ÷ 2
= 8 u
= 8 x 10
= 80

Answer(s): 80