Answer is 84 miles You can use the y intercept method of solving this Y= mx + b Y is your total cost 55.20 M is your slope or rate of .30/1 mile B is your intercept or starting point $30 So fill in your known numbers 55.20 = .30x + $30 Isolate x by subtracting $30 from both sides 55.20 - 30 = .30x + 30 - 30 25.20 = .30x Now solve for x by dividing both sides by .30 25.20 / .30 = 84 miles Problem solved