Winnie has 30% as many marbles as Gwen. Gwen has 140% as many marbles as Eva. If Gwen gives 80 marbles to Eva, both will then have an equal number of marbles. Find the average number of marbles the three of them have.

Winnie	Gwen	Eva
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

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

	Gwen	Eva	Total
Before	70 u	50 u	120 u
Change	- 10 u	+ 10 u
After	60 u	60 u	120 u

Total number of marbles that Gwen and Eva have
= 70 u + 50 u
= 120 u

After Gwen gives to Eva, both of them will have the same number of marbles. 

The total number of marbles that Gwen and Eva have remains unchanged.

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

Number of marbles that Gwen gives to Eva
= 70 u - 60 u
= 10 u

10 u = 80

1 u = 80 ÷ 10 = 8

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

Average number of marbles that each of them have
= 141 u ÷ 3
= 47 u
= 47 x 8
= 376

Answer(s): 376