Anna and Natalie collected stamps. Anna gave 50% of her stamps to Natalie and as a result, Natalie's stamps increased by 30%. If Anna had 21 stamps left, find the number of stamps Natalie should give to Anna in the end so that both had an equal number of stamps.

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

3 u = 21

1 u = 21 ÷ 3 = 7

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

Number of stamps that Natalie should give to Anna so that both had an equal number of stamps in the end
= 10 u ÷ 2
= 5 u
= 5 x 7
= 35

Answer(s): 35