Hold on, what kind of maths is that.You saw a shirt worth $97 and since you don't have the money available you borrowed $50 from your Mom and $50 from your Dad. So, you have $100 and since the shirt is only $97 you have $3 left after paying for the shirt. You give back $1 to your Mom and $1 to your Dad and you are therefor left with $1. Now you owe your Mom $49 and your Dad $49. So, $49+$49=$98 plus the $1 you have = $99. WHERE IS THE MISSING $1?