Sunni drives total of sixty-four and half mile to work and back each day Monday through friday. Her car gets 21.5miles per gallon. if has cost $2.85 per gallon, how much does it cost Sunni to drive and from work each week?

Alright, so she drives 64.5*5 (for 5 days) = 322.5 miles each week. She then uses 322.5miles/1 * 1gallon/21.5 miles (we have 1 gallon/21.5 miles because 1 gallon=21.5 miles and we have the gallon at the top to cross the miles out) = 15 gallons. The cost per gallon is 2.85 (we add 2.85 for each gallon), and we have 15 gallons, so 2.85dollars*15l=42.75 dollars is our answer