Why can't you show me how to set up the problem

How do i do this? i don’t understand

Which expression will have the same sum as 3_8 + 1/4?

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?