Tina and Lynn collected postcards. Tina gave 30% of her postcards to Lynn and as a result, Lynn's postcards increased by 25%. If Tina had 28 postcards left, find the number of postcards Lynn should give to Tina in the end so that both had an equal number of postcards.

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

7 u = 28

1 u = 28 ÷ 7 = 4

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

Number of postcards that Lynn should give to Tina so that both had an equal number of postcards in the end
= 8 u ÷ 2
= 4 u
= 4 x 4
= 16

Answer(s): 16