Olivia has 30% as many stamps as Tiffany. Tiffany has 110% as many stamps as Eva. If Tiffany gives 20 stamps to Eva, both will then have an equal number of stamps. Find the average number of stamps the three of them have.

Olivia	Tiffany	Eva
3x11	10x11
	11x10	10x10
33 u	110 u	100 u

30% = ³⁰₁₀₀ = ³₁₀
110% = ¹¹⁰₁₀₀= ¹¹₁₀

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

	Tiffany	Eva	Total
Before	110 u	100 u	210 u
Change	- 5 u	+ 5 u
After	105 u	105 u	210 u

Total number of stamps that Tiffany and Eva have
= 110 u + 100 u
= 210 u

After Tiffany gives to Eva, both of them will have the same number of stamps. 

The total number of stamps that Tiffany and Eva have remains unchanged.

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

Number of stamps that Tiffany gives to Eva
= 110 u - 105 u
= 5 u

5 u = 20

1 u = 20 ÷ 5 = 4

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

Average number of stamps that each of them have
= 243 u ÷ 3
= 81 u
= 81 x 4
= 324

Answer(s): 324