Julie and Marion collected marbles. Julie gave 50% of her marbles to Marion and as a result, Marion's marbles increased by 30%. If Julie had 12 marbles left, find the number of marbles Marion should give to Julie in the end so that both had an equal number of marbles.

	Julie	Marion	Comparing the change in Marion's marbles
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 marbles that Marion had is repeated.  Make the increase in the number of marbles that Marion had the same. LCM of 1 and 3 = 3

3 u = 12

1 u = 12 ÷ 3 = 4

Number of marbles that Marion had more than Julie in the end
= 13 u - 3 u
= 10 u

Number of marbles that Marion should give to Julie so that both had an equal number of marbles in the end
= 10 u ÷ 2
= 5 u
= 5 x 4
= 20

Answer(s): 20