I don’t know the reverse operation to this

Plz which expression is equivalent to the expression below?

What are the equivalent ratios for 24/2= /3= /5.5=108/ = /15

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?