Gwen and Sabrina collected stamps. Gwen gave 50% of her stamps to Sabrina and as a result, Sabrina's stamps increased by 30%. If Gwen had 18 stamps left, find the number of stamps Sabrina should give to Gwen in the end so that both had an equal number of stamps.

	Gwen	Sabrina	Comparing the change in Sabrina's stamps
Before	2x3 = 6 u		10x1 = 10u
Change	- 1x3 = - 3 u	+ 1x3 = + 3 u	+ 3x1 = + 3 u
After	1x3 = 3 u		13x1 = 13 u

50% = ⁵⁰₁₀₀ = ¹₂
30% = ³⁰₁₀₀ = ³₁₀

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

3 u = 18

1 u = 18 ÷ 3 = 6

Number of stamps that Sabrina had more than Gwen in the end
= 13 u - 3 u
= 10 u

Number of stamps that Sabrina should give to Gwen so that both had an equal number of stamps in the end
= 10 u ÷ 2
= 5 u
= 5 x 6
= 30

Answer(s): 30