Help me please I’m desprate

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?

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

If f(x) = 4 - x2 and g(x) = 6x, which expression is equivalent to (g-f)(3)? 06-3-(4 + 3)2 06-3-(4-33 6(3) - 4 +32 6(3) -4 -32