Rachel and Fiona collected marbles. Rachel gave 30% of her marbles to Fiona and as a result, Fiona's marbles increased by 25%. If Rachel had 28 marbles left, find the number of marbles Fiona should give to Rachel in the end so that both had an equal number of marbles.

	Rachel	Fiona	Comparing the change in Fiona's marbles
Before	10x1 = 10 u		4x3 = 12u
Change	- 3x1 = - 3 u	+ 3x1 = + 3 u	+ 1x3 = + 3 u
After	7x1 = 7 u		5x3 = 15 u

30% = ³⁰₁₀₀ = ³₁₀
25% = ²⁵₁₀₀ = ¹₄

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

7 u = 28

1 u = 28 ÷ 7 = 4

Number of marbles that Fiona had more than Rachel in the end
= 15 u - 7 u
= 8 u

Number of marbles that Fiona should give to Rachel so that both had an equal number of marbles in the end
= 8 u ÷ 2
= 4 u
= 4 x 4
= 16

Answer(s): 16