The function f(x) = x + 18 is one-to-one.Find an equation for f1(x), the inverse function.f-(x) = [(Type an expression for the inverse. Use integers

The function f(x) = x + 18 is one-to-one.Find an equation for f1(x), the inverse function.f-¹(x) = [(Type an expression for the inverse. Use integers or fractions for any numbers in the expression.)