Mary, Marion and Cindy each had some marbles and decided to play a game with their marbles. In round 1, Mary lost ¹₂ of her marbles to Marion. In round 2, Marion lost ¹₂ of her total number of marbles to Cindy. In round 3, Cindy lost ¹₂ of her total number of marbles to Mary. In the end, Mary, Marion and Cindy had 128, 93 and 73 marbles respectively. How many marbles did Marion have at first?

	Mary	Marion	Cindy
Before  1	2 b	131
Change 1	- 1 b	+ 1 b
After 1	1 b	186
Before 2	55	2 u
Change 2		- 1 u	+1
After 2		1 u	146
Before 3			2 p
Change 3	+ 1 p		- 1 p
After 3			1 p
Comparing Mary, Marion and Cindy in the end	128	93	73

Working backwards.

1 p = 73

At the start of Round 3:
Number of marbles that Cindy had
= 2 p
= 2 x 73 
= 146

At the start of Round 2:
Number of marbles that Mary had
= 128 - 1 p
= 128 - 73
= 55

At the end of Round 3:
Number of marbles that Marion had = 93

1 u = 93

At the end of Round 1:
Number of marbles that Marion had
= 2 u
= 2 x 93 
= 186

1 b = 55 

At the end of Round 1:
Number of marbles that Mary had = 55

At the start of Round 1:
Number of marbles that Marion had
= 186 - 1 b
= 186 - 55
= 131

Answer(s): 131