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

	Kimberly	Irene	Comparing the change in Irene'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 Irene had is repeated.  Make the increase in the number of coins that Irene had the same. LCM of 3 and 1 = 3

7 u = 42

1 u = 42 ÷ 7 = 6

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

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

Answer(s): 78