Example 8 in section 3.2 describes fuel cost involved in idling your car engine for 5 minutes per day when the cost of gasoline is $3.75 per gallon using the formula c = 19a – 4 where c is the cost and a is the size of the engine in liters. determine the size of the engine in your car and find the cost of idling your car engine for 5 minutes per day.