Winnie and Hilda collected postcards. Winnie gave 25% of her postcards to Hilda and as a result, Hilda's postcards increased by 30%. If Winnie had 54 postcards left, find the number of postcards Hilda should give to Winnie in the end so that both had an equal number of postcards.

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

9 u = 54

1 u = 54 ÷ 9 = 6

Number of postcards that Hilda had more than Winnie in the end
= 13 u - 9 u
= 4 u

Number of postcards that Hilda should give to Winnie so that both had an equal number of postcards in the end
= 4 u ÷ 2
= 2 u
= 2 x 6
= 12

Answer(s): 12