Emma and Lynn collected postcards. Emma gave 60% of her postcards to Lynn and as a result, Lynn's postcards increased by 20%. If Emma had 18 postcards left, find the number of postcards Lynn should give to Emma in the end so that both had an equal number of postcards.

	Emma	Lynn	Comparing the change in Lynn's postcards
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 postcards that Lynn had is repeated.  Make the increase in the number of postcards that Lynn had the same. LCM of 3 and 1 = 3

2 u = 18

1 u = 18 ÷ 2 = 9

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

Number of postcards that Lynn should give to Emma so that both had an equal number of postcards in the end
= 16 u ÷ 2
= 8 u
= 8 x 9
= 72

Answer(s): 72