Hazel and Xuan collected marbles. Hazel gave 25% of her marbles to Xuan and as a result, Xuan's marbles increased by 30%. If Hazel had 72 marbles left, find the number of marbles Xuan should give to Hazel in the end so that both had an equal number of marbles.

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

9 u = 72

1 u = 72 ÷ 9 = 8

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

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

Answer(s): 16