A student saves $15 per week toward the purchase of a guitar. Her grandmother gives her $50 to help her reach her goal. Which function can be used to find the amount in dollars the student has saved after x weeks?

Elena and her husband marc both drive to work. elena's car has a current mileage (total distance driven) of 15,000 and she drives 23,000 miles more each year. marc's car has a current mileage of 46,000 and he drives 9,000 miles more each year. will the mileages for the two cars ever be equal? explain.