Mathematics
what the average of 25,30,45,35,50?

Can someone explain the elimination method to me for this problem?

Negative 5 1/12 + negative 4 1/4 + 6 3/4

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?