Javonne purchased some art supplies and paid for them with a $20 bill. The cashier handed her c dollars in change, which was a mistake. To fix the mistake, Javonne returned $1.00 to the cashier. If the purchase price was twice the amount of change Javonne was originally given, what is the value of c? A) $5.50 B) $7.00 C) $9.50 D) $10.50