Answer:
Future cost per gallon= $15.05
Explanation:
Giving the following information: 
Oil prices are projected to increase by 75% by next May. A quart of oil currently costs $2.15. 
We know that 1 quart equals 0.25 gallons. 
First, we will determine the actual cost per gallon.
Actual cost per gallon= 2.15*4= $8.6
Now, the cost for May:
Future cost per gallon= 8.6*1.75
Future cost per gallon= $15.05