A truck rental company charges a one-
 time fee of $40 plus $1 per mile driven.
 Dalia rented a truck and used a coupon
 for 20% off the total rental cost. After the
 coupon was applied, she spent a total of
 $60. How many miles did she drive?
 A. 8
 B. 20
 C. 32
 D. 35