Xandra and Diana collected postcards. Xandra gave 30% of her postcards to Diana and as a result, Diana's postcards increased by 25%. If Xandra had 63 postcards left, find the number of postcards Diana should give to Xandra in the end so that both had an equal number of postcards.

	Xandra	Diana	Comparing the change in Diana's postcards
Before	10x1 = 10 u		4x3 = 12u
Change	- 3x1 = - 3 u	+ 3x1 = + 3 u	+ 1x3 = + 3 u
After	7x1 = 7 u		5x3 = 15 u

30% = ³⁰₁₀₀ = ³₁₀
25% = ²⁵₁₀₀ = ¹₄

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

7 u = 63

1 u = 63 ÷ 7 = 9

Number of postcards that Diana had more than Xandra in the end
= 15 u - 7 u
= 8 u

Number of postcards that Diana should give to Xandra so that both had an equal number of postcards in the end
= 8 u ÷ 2
= 4 u
= 4 x 9
= 36

Answer(s): 36