Mary and Lucy collected erasers. Mary gave 30% of her erasers to Lucy and as a result, Lucy's erasers increased by 25%. If Mary had 49 erasers left, find the number of erasers Lucy should give to Mary in the end so that both had an equal number of erasers.

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

7 u = 49

1 u = 49 ÷ 7 = 7

Number of erasers that Lucy had more than Mary in the end
= 15 u - 7 u
= 8 u

Number of erasers that Lucy should give to Mary so that both had an equal number of erasers in the end
= 8 u ÷ 2
= 4 u
= 4 x 7
= 28

Answer(s): 28