If you borrow $50 from your mom and $50 from your dad it makes $100. So the shirt you buy is $97. Then you have $3 left. So you
keep $1 and you give $1 to your mom and $1 to your dad. So now u owe them $49 each. $49 plus $49 is $98 plus then $1 you have it is $99. So where is the other $1.
That is a bit bewildering!! The only thing I can think of is you are adding the quantities in the wrong way. From your standpoint your balance after you borrowed the money was -$100 and you spent $97 leaving you with $3. So you have to give back $97 and $3, and -100 + 97 + 3 = 0.
