Can someone help me on my question pls

This is different from the first one can someone me

The total cost of anja’s trip to the dentist was $628.35. she paid a flat fee of $89.95 which included the checkup and cleaning and then had 4 cavities filled, each of which cost the same amount. which shows the correct equation and value of x, the cost of each cavity filling?

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)