Homework help with an algebraic equation D:?

Question

A rental car costs a minimum charge plus a fixed charge per mile driven. One customer was charged $60 for 160 miles of use and another customer drove 280 miles and paid $90. write an equation relating the total cost, C (in dollars) to the miles driven X.

Need help!

Answer 1

Let the fixed charge be f and the cost per mile be m.  Then your equation would be

C = f + mX

You have two points:

60 = f + m(160)

and

90 = f + m(280)

Two equations, two unknowns - you can solve this.