Lucy and Fiona collected marbles. Lucy gave 25% of her marbles to Fiona and as a result, Fiona's marbles increased by 30%. If Lucy had 99 marbles left, find the number of marbles Fiona should give to Lucy in the end so that both had an equal number of marbles.

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

9 u = 99

1 u = 99 ÷ 9 = 11

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

Number of marbles that Fiona should give to Lucy so that both had an equal number of marbles in the end
= 4 u ÷ 2
= 2 u
= 2 x 11
= 22

Answer(s): 22