Risa and Erika collected stamps. Risa gave 60% of her stamps to Erika and as a result, Erika's stamps increased by 20%. If Risa had 24 stamps left, find the number of stamps Erika should give to Risa in the end so that both had an equal number of stamps.

	Risa	Erika	Comparing the change in Erika'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 Erika had is repeated.  Make the increase in the number of stamps that Erika had the same. LCM of 3 and 1 = 3

2 u = 24

1 u = 24 ÷ 2 = 12

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

Number of stamps that Erika should give to Risa so that both had an equal number of stamps in the end
= 16 u ÷ 2
= 8 u
= 8 x 12
= 96

Answer(s): 96