Gwen has 30% as many erasers as Anna. Anna has 110% as many erasers as Opal. If Anna gives 40 erasers to Opal, both will then have an equal number of erasers. Find the average number of erasers the three of them have.

Gwen	Anna	Opal
3x11	10x11
	11x10	10x10
33 u	110 u	100 u

30% = ³⁰₁₀₀ = ³₁₀
110% = ¹¹⁰₁₀₀= ¹¹₁₀

The number of erasers that Gwen has is repeated.  Make the number of erasers that Gwen has the same. LCM of 10 and 11 is 110.

	Anna	Opal	Total
Before	110 u	100 u	210 u
Change	- 5 u	+ 5 u
After	105 u	105 u	210 u

Total number of erasers that Anna and Opal have
= 110 u + 100 u
= 210 u

After Anna gives to Opal, both of them will have the same number of erasers. 

The total number of erasers that Anna and Opal have remains unchanged.

Number of erasers that each of them will have
= 210 u ÷ 2
= 105 u

Number of erasers that Anna gives to Opal
= 110 u - 105 u
= 5 u

5 u = 40

1 u = 40 ÷ 5 = 8

Total number of erasers that three of them have
= 210 u + 33 u
= 243 u

Average number of erasers that each of them have
= 243 u ÷ 3
= 81 u
= 81 x 8
= 648

Answer(s): 648