Shiyun has 30% as many erasers as Lucy. Lucy has 110% as many erasers as Tina. If Lucy gives 30 erasers to Tina, both will then have an equal number of erasers. Find the average number of erasers the three of them have.

Shiyun	Lucy	Tina
3x11	10x11
	11x10	10x10
33 u	110 u	100 u

30% = ³⁰₁₀₀ = ³₁₀
110% = ¹¹⁰₁₀₀= ¹¹₁₀

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

	Lucy	Tina	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 Lucy and Tina have
= 110 u + 100 u
= 210 u

After Lucy gives to Tina, both of them will have the same number of erasers. 

The total number of erasers that Lucy and Tina have remains unchanged.

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

Number of erasers that Lucy gives to Tina
= 110 u - 105 u
= 5 u

5 u = 30

1 u = 30 ÷ 5 = 6

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 6
= 486

Answer(s): 486