Barbara has 30% as many marbles as Jaslyn. Jaslyn has 140% as many marbles as Winnie. If Jaslyn gives 50 marbles to Winnie, both will then have an equal number of marbles. Find the average number of marbles the three of them have.

Barbara	Jaslyn	Winnie
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

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

	Jaslyn	Winnie	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 Jaslyn and Winnie have
= 70 u + 50 u
= 120 u

After Jaslyn gives to Winnie, both of them will have the same number of marbles. 

The total number of marbles that Jaslyn and Winnie have remains unchanged.

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

Number of marbles that Jaslyn gives to Winnie
= 70 u - 60 u
= 10 u

10 u = 50

1 u = 50 ÷ 10 = 5

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 5
= 235

Answer(s): 235