Cathy and Fanny collected stickers. Cathy gave 25% of her stickers to Fanny and as a result, Fanny's stickers increased by 30%. If Cathy had 90 stickers left, find the number of stickers Fanny should give to Cathy in the end so that both had an equal number of stickers.

	Cathy	Fanny	Comparing the change in Fanny's stickers
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 stickers that Fanny had is repeated.  Make the increase in the number of stickers that Fanny had the same. LCM of 1 and 3 = 3

9 u = 90

1 u = 90 ÷ 9 = 10

Number of stickers that Fanny had more than Cathy in the end
= 13 u - 9 u
= 4 u

Number of stickers that Fanny should give to Cathy so that both had an equal number of stickers in the end
= 4 u ÷ 2
= 2 u
= 2 x 10
= 20

Answer(s): 20