I saw a shirt for $97, I borrowed $50 from dad and $50 from mom. I bought the shirt for $97 with $3 change in hand $100-$97 = $3. Now I gave $1 to dad and $1 to mom and kept $1 to myself. Now I owe my dad $49 my mom $49, and I have $1($49+$49+$1 = $99). But where did $1 go, as I had $100, to begin with?