Solution!
The dollar didn't go anywhere!
If you originally obtained $100, $50 from mom and $50 from dad, and spend $97 on the shirt, you have $3 left.
If you give $1 back to mom, then you owe her $49.
If you give $1 back to dad, then you owe him $49.
$49+$49=$98
so, $98=$97 shirt+$1 kept for yourself
The $98 already includes the $1 you kept for yourself, so you can't add it again.
So, $98 (shirt plus $1 you kept)+$1 (for mom)+$1 (for dad)=$100 (started with).
If you originally obtained $100, $50 from mom and $50 from dad, and spend $97 on the shirt, you have $3 left.
If you give $1 back to mom, then you owe her $49.
If you give $1 back to dad, then you owe him $49.
$49+$49=$98
so, $98=$97 shirt+$1 kept for yourself
The $98 already includes the $1 you kept for yourself, so you can't add it again.
So, $98 (shirt plus $1 you kept)+$1 (for mom)+$1 (for dad)=$100 (started with).