Elyse and Betty collected postcards. Elyse gave 30% of her postcards to Betty and as a result, Betty's postcards increased by 10%. If Elyse had 56 postcards left, find the number of postcards Betty should give to Elyse in the end so that both had an equal number of postcards.

	Elyse	Betty	Comparing the change in Betty's postcards
Before	10x1 = 10 u		10x3 = 30u
Change	- 3x1 = - 3 u	+ 3x1 = + 3 u	+ 1x3 = + 3 u
After	7x1 = 7 u		11x3 = 33 u

30% = ³⁰₁₀₀ = ³₁₀
10% = ¹⁰₁₀₀ = ¹₁₀

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

7 u = 56

1 u = 56 ÷ 7 = 8

Number of postcards that Betty had more than Elyse in the end
= 33 u - 7 u
= 26 u

Number of postcards that Betty should give to Elyse so that both had an equal number of postcards in the end
= 26 u ÷ 2
= 13 u
= 13 x 8
= 104

Answer(s): 104