Roshel and Marion collected coins. Roshel gave 30% of her coins to Marion and as a result, Marion's coins increased by 10%. If Roshel had 42 coins left, find the number of coins Marion should give to Roshel in the end so that both had an equal number of coins.

	Roshel	Marion	Comparing the change in Marion's coins
Before	10x1 = 10 u		10x3 = 30u
Change	- 3x1 = - 3 u	+ 3x1 = + 3 u	+ 1x3 = + 3 u
After	7x1 = 7 u		11x3 = 33 u

30% = ³⁰₁₀₀ = ³₁₀
10% = ¹⁰₁₀₀ = ¹₁₀

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

7 u = 42

1 u = 42 ÷ 7 = 6

Number of coins that Marion had more than Roshel in the end
= 33 u - 7 u
= 26 u

Number of coins that Marion should give to Roshel so that both had an equal number of coins in the end
= 26 u ÷ 2
= 13 u
= 13 x 6
= 78

Answer(s): 78