Sarah and Emma collected marbles. Sarah gave 60% of her marbles to Emma and as a result, Emma's marbles increased by 20%. If Sarah had 20 marbles left, find the number of marbles Emma should give to Sarah in the end so that both had an equal number of marbles.

	Sarah	Emma	Comparing the change in Emma's marbles
Before	5x1 = 5 u		5x3 = 15u
Change	- 3x1 = - 3 u	+ 3x1 = + 3 u	+ 1x3 = + 3 u
After	2x1 = 2 u		6x3 = 18 u

60% = ⁶⁰₁₀₀ = ³₅
20% = ²⁰₁₀₀ = ¹₅

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

2 u = 20

1 u = 20 ÷ 2 = 10

Number of marbles that Emma had more than Sarah in the end
= 18 u - 2 u
= 16 u

Number of marbles that Emma should give to Sarah so that both had an equal number of marbles in the end
= 16 u ÷ 2
= 8 u
= 8 x 10
= 80

Answer(s): 80