I borrow 50 dollars from A and 50 Dollars from B, which amount to 100 dollars. I bought a pair of sport shoes costing 97 dollars. Leaving 3 dollars to me. I gave 1 dollar to A and B each, while I took the other 1 dollar. This means that I owe A and B 49 dollars each, right? But this means that 49+49+1=99 dollars where is the other dollar? This question was asked by my friend in school, tricky,eh?:confused:

Not really.

If you borrow $50 from A and $50 from B, and paid them back $1, then you now owe each of them $49.

When you add $49 + $49 + $1, the result has only a minor relationship to the original $100 and is deceiving. The $1 you have in your hand is part of what you borrowed. $49 + $49 = $98 -- that what you still owe because you paid back $2. The original debt is found from $98 + $2 = $100.

This is a twist on the famous 'missing dollar problem'.