Ineed ! i'm stuck on answering these

Which inequality comparing two of the expressions is true when 0.7 < x < 0.9

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?

Plz hurry evaluate the expression a+b where a=8 and b=19