Opal has 30% as many coins as Joelle. Joelle has 140% as many coins as Yoko. If Joelle gives 30 coins to Yoko, both will then have an equal number of coins. Find the average number of coins the three of them have.

Opal	Joelle	Yoko
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

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

	Joelle	Yoko	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 Joelle and Yoko have
= 70 u + 50 u
= 120 u

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

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

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

Number of coins that Joelle gives to Yoko
= 70 u - 60 u
= 10 u

10 u = 30

1 u = 30 ÷ 10 = 3

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 3
= 141

Answer(s): 141