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

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

9 u = 72

1 u = 72 ÷ 9 = 8

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

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

Answer(s): 16