Xandra has 25% as many erasers as Cindy. Cindy has 130% as many erasers as Sarah. If Cindy gives 12 erasers to Sarah, both will then have an equal number of erasers. Find the average number of erasers the three of them have.

Xandra	Cindy	Sarah
1x13	4x13
	13x4	10x4
13 u	52 u	40 u

25% = ²⁵₁₀₀ = ¹₄
130% = ¹³⁰₁₀₀= ¹³₁₀

The number of erasers that Xandra has is repeated.  Make the number of erasers that Xandra has the same. LCM of 4 and 13 is 52.

	Cindy	Sarah	Total
Before	52 u	40 u	92 u
Change	- 6 u	+ 6 u
After	46 u	46 u	92 u

Total number of erasers that Cindy and Sarah have
= 52 u + 40 u
= 92 u

After Cindy gives to Sarah, both of them will have the same number of erasers. 

The total number of erasers that Cindy and Sarah have remains unchanged.

Number of erasers that each of them will have
= 92 u ÷ 2
= 46 u

Number of erasers that Cindy gives to Sarah
= 52 u - 46 u
= 6 u

6 u = 12

1 u = 12 ÷ 6 = 2

Total number of erasers that three of them have
= 92 u + 13 u
= 105 u

Average number of erasers that each of them have
= 105 u ÷ 3
= 35 u
= 35 x 2
= 70

Answer(s): 70