Question 799605
Stu had quite a collection of baseball cards.  One day he decided to give half of them to his brother Seth.  Then he gave one-third of what he had left to a friend.  Then he gave half of what was left to another friend.  Stu now has 50 baseball cards.  How many did he start with?  It seems that I should work 

let Stu have x cards

he gave half to seth
so he had x/2 cards

He had x/2 he gave 1/3 of x/2 to a friend 

=x/6.

Now he had x/2 - x/6 = x/3 with him balance

1/2 of x/3 he gave to another friend =x/6 

Balance he had was x/3 - x/6 = x/6

x/6 = 50

multiply by 6
x= 300