February 28, 2000
Problem of the Month

The Store Problem

A man goes into a store and says to the owner: "Give me as much money as I have with me and I will spend $10."

It is done and the man repeats the operation at a second and a third store, after which he has no money left.

How much did he start with?

Solution to the Problem:

The answer is $8.75

Let x = how much the man started with.

Then in the first store:
x + x - 10 is how much he had left.

In the second store:
(2x-10) + (2x-10) - 10 is how much is left
This simplifies to 4x - 30

In the third store:
(4x-30) + (4x-30) - 10 is how much is left
This simplifies to 8x - 70

So, 8x - 70 = 0 (no money left)
8x = 70
x = 70/8 or $8.75

Correctly solved by:

1. Richard Mocarski	Winchester, VA
2. Chip Crawford	Winchester, VA
3. Sam Stiebel	Winchester, VA
4. Kirstine Wynn	Winchester, VA
5. Elizabeth Cotter	Oak Hill, VA
6. Tom Marino	Winchester, VA
7. Court Pifer	Winchester, VA
8. Joe Jenkins	Winchester, VA
9. Eric Harding	McLean, VA
10. Zinedine Zindane	Marseille, France
11. John Pence	Winchester, VA
12. Ryan Throckmorton	Winchester, VA

Send any comments or questions to: David Pleacher