Rachel and Lucy collected postcards. Rachel gave 30% of her postcards to Lucy and as a result, Lucy's postcards increased by 10%. If Rachel had 35 postcards left, find the number of postcards Lucy should give to Rachel in the end so that both had an equal number of postcards.

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

7 u = 35

1 u = 35 ÷ 7 = 5

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

Number of postcards that Lucy should give to Rachel so that both had an equal number of postcards in the end
= 26 u ÷ 2
= 13 u
= 13 x 5
= 65

Answer(s): 65