If the function f(x) = x+b has an inverse function, which statement must be true? 772 = 0 b = 0

Does anyone know this? the andwer choices are: 79, 85, 101, and 135 degrees!

The number of revolutions of two pulleys is inversely proportional to their diameters. if a 24-inch diameter pulley making 400 revolutions per minute is belted to an 8-inch diameter pulley, find the number of revolutions per minute of the smaller pulley.

If f(x)= 3x+6 which of the following is the inverse of f(x)