I need help with knowing what is the ray? help please

What is the missing constant term in the perfect square that starts with x^2 -20x

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.

Need this asap if anyone can i would be very grateful. if you could show workings that would really