Ineed with 18 and can you show work because i don't know how to show work

What is f(3) for the quadratic function f(x)= 2x^2+ + x - 12

Match each expression with its simplified form.

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.