Im clueless... someone plz help

Solve 2x+y=3 x+y=5 in substitution method

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?

Which representation has a constant of variation of -2.5