Risa has 30% as many coins as Erika. Erika has 140% as many coins as Tammy. If Erika gives 60 coins to Tammy, both will then have an equal number of coins. Find the average number of coins the three of them have.

Risa	Erika	Tammy
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

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

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

Total number of coins that Erika and Tammy have
= 70 u + 50 u
= 120 u

After Erika gives to Tammy, both of them will have the same number of coins. 

The total number of coins that Erika and Tammy have remains unchanged.

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

Number of coins that Erika gives to Tammy
= 70 u - 60 u
= 10 u

10 u = 60

1 u = 60 ÷ 10 = 6

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

Average number of coins that each of them have
= 141 u ÷ 3
= 47 u
= 47 x 6
= 282

Answer(s): 282