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

Diana	Sabrina	Anna
3x11	10x11
	11x10	10x10
33 u	110 u	100 u

30% = ³⁰₁₀₀ = ³₁₀
110% = ¹¹⁰₁₀₀= ¹¹₁₀

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

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

Total number of coins that Sabrina and Anna have
= 110 u + 100 u
= 210 u

After Sabrina gives to Anna, both of them will have the same number of coins. 

The total number of coins that Sabrina and Anna have remains unchanged.

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

Number of coins that Sabrina gives to Anna
= 110 u - 105 u
= 5 u

5 u = 40

1 u = 40 ÷ 5 = 8

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

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

Answer(s): 648