Fiona has 30% as many erasers as Lynn. Lynn has 140% as many erasers as Erika. If Lynn gives 110 erasers to Erika, both will then have an equal number of erasers. Find the average number of erasers the three of them have.

Fiona	Lynn	Erika
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

The number of erasers that Fiona has is repeated.  Make the number of erasers that Fiona has the same. LCM of 10 and 7 is 70.

	Lynn	Erika	Total
Before	70 u	50 u	120 u
Change	- 10 u	+ 10 u
After	60 u	60 u	120 u

Total number of erasers that Lynn and Erika have
= 70 u + 50 u
= 120 u

After Lynn gives to Erika, both of them will have the same number of erasers. 

The total number of erasers that Lynn and Erika have remains unchanged.

Number of erasers that each of them will have
= 120 u ÷ 2
= 60 u

Number of erasers that Lynn gives to Erika
= 70 u - 60 u
= 10 u

10 u = 110

1 u = 110 ÷ 10 = 11

Total number of erasers that three of them have
= 120 u + 21 u
= 141 u

Average number of erasers that each of them have
= 141 u ÷ 3
= 47 u
= 47 x 11
= 517

Answer(s): 517