Question

Chris spent half of his money on a pair of headphones. Then he spends half of his remaining money of recordable CDs. Finally, he spent his remaining $12.75 on a book. How much money did Chris have to begin with?

Answer 1

I think the answer would be $50.50

Answer 2

Assume that Chris began with m dollars in his pocket.

Half of that, or m/2, went to purchase a pair of headphones.

Half of that, or (1/2)(m/2), or m/4, went to purchasing CDs.  By now Chris has spent (1/2 + 1/4) of his money:  (3/4)m.  He had (1/4)m left, and that (m/4) = $12.75.

Solve this for m:
         $12.75
m = ------------ = $5 (answer).    
            (1/4)