Fiona and Joelle collected coins. Fiona gave 25% of her coins to Joelle and as a result, Joelle's coins increased by 30%. If Fiona had 90 coins left, find the number of coins Joelle should give to Fiona in the end so that both had an equal number of coins.

	Fiona	Joelle	Comparing the change in Joelle's coins
Before	4x3 = 12 u		10x1 = 10u
Change	- 1x3 = - 3 u	+ 1x3 = + 3 u	+ 3x1 = + 3 u
After	3x3 = 9 u		13x1 = 13 u

25% = ²⁵₁₀₀ = ¹₄
30% = ³⁰₁₀₀ = ³₁₀

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

9 u = 90

1 u = 90 ÷ 9 = 10

Number of coins that Joelle had more than Fiona in the end
= 13 u - 9 u
= 4 u

Number of coins that Joelle should give to Fiona so that both had an equal number of coins in the end
= 4 u ÷ 2
= 2 u
= 2 x 10
= 20

Answer(s): 20