The inverse of f(x) = 1/3 x + 5 would be equal to switching the x and y (independent and dependent variables) and then solving for y.The first step in finding the inverse is switching the x and y (to see the problem easier, f(x) = y).x = 1/3 y + 5Since the x value is given, substitute 3 for x.3 = 1/3 y + 5Now the function must be solved for y.-2 = 1/3 y-6 = ySo, the y-value for x = 3 of f^-1(x) is -6.