You saw a shirt for $97. You didn't have the cash, so you borrowed $50 from your mom and $50 from your dad = $100. You bought the shirt, and had $3 change. You gave your dad $1 and your mom $1 and kept the other $1 for yourself. Now you owe your mom $49 and your dad $49. 49 49 = 98 your $1 = 99. Where is the missing $1?

You have it! You should subtract your dollar not add it!