You see an item for $97.
You borrow $50 from your mum, $50 from your dad ($100) and purchase the item.
Of the $3 dollars change you give your mum $1 and your dad $1 and keep $1.
You now owe both mum and dad $49 each.
2x$49= $98 + the $1 you have = $99.
What happened to the $1.
