Urgent!! (question in screenshot)

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

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?

Is the square root of 4 plus the square root of 16 rational?