Rachel has 30% as many coins as Zara. Zara has 140% as many coins as Shiyun. If Zara gives 50 coins to Shiyun, both will then have an equal number of coins. Find the average number of coins the three of them have.

Rachel	Zara	Shiyun
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

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

	Zara	Shiyun	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 Zara and Shiyun have
= 70 u + 50 u
= 120 u

After Zara gives to Shiyun, both of them will have the same number of coins. 

The total number of coins that Zara and Shiyun have remains unchanged.

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

Number of coins that Zara gives to Shiyun
= 70 u - 60 u
= 10 u

10 u = 50

1 u = 50 ÷ 10 = 5

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 5
= 235

Answer(s): 235