Emma has 30% as many coins as Kathy. Kathy has 110% as many coins as Joelle. If Kathy gives 25 coins to Joelle, both will then have an equal number of coins. Find the average number of coins the three of them have.

Emma	Kathy	Joelle
3x11	10x11
	11x10	10x10
33 u	110 u	100 u

30% = ³⁰₁₀₀ = ³₁₀
110% = ¹¹⁰₁₀₀= ¹¹₁₀

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

	Kathy	Joelle	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 Kathy and Joelle have
= 110 u + 100 u
= 210 u

After Kathy gives to Joelle, both of them will have the same number of coins. 

The total number of coins that Kathy and Joelle have remains unchanged.

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

Number of coins that Kathy gives to Joelle
= 110 u - 105 u
= 5 u

5 u = 25

1 u = 25 ÷ 5 = 5

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 5
= 405

Answer(s): 405