Help me with my math please!

What is the vertex form of f(x) = x2 + 6x + 3

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.

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)