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

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

9 u = 90

1 u = 90 ÷ 9 = 10

Number of erasers that Anna had more than Nicole in the end
= 13 u - 9 u
= 4 u

Number of erasers that Anna should give to Nicole so that both had an equal number of erasers in the end
= 4 u ÷ 2
= 2 u
= 2 x 10
= 20

Answer(s): 20