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

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

3 u = 21

1 u = 21 ÷ 3 = 7

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

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

Answer(s): 35