9) Sarah Ouellette has leased a new automobile under a special lease plan. If she drives the car 1,000 miles or less during a one-month period, the lease payment is $250.If the mileage ranges between 1,001 and 1,500 miles, the lease payment becomes $300. If the mileage ranges between 1,5001 and 2,000 miles, the lease payment rises to $350 Required: a) What type of cost is the lease? b) If Sarah only drives the car between 1,200 and 1,400 miles per month, then what type of cost does the lease effectively become?