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

Yen	Linda	Gwen
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

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

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

Total number of cards that Linda and Gwen have
= 70 u + 50 u
= 120 u

After Linda gives to Gwen, both of them will have the same number of cards. 

The total number of cards that Linda and Gwen have remains unchanged.

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

Number of cards that Linda gives to Gwen
= 70 u - 60 u
= 10 u

10 u = 80

1 u = 80 ÷ 10 = 8

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

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

Answer(s): 376