The equation y = 4.75x + 20 gives the cost y of towing a car if the car is towed x miles. which statement is true?
a. for every mile the car is towed, the cost decreases by $20.
b. for every mile the car is towed, the cost decreases by $4.75.
c. for every mile the car is towed, the cost increases by $4.75.
d. for every mile the car is towed, the cost increases by $20.