Chapter 8.4A, Problem 14A

Consider the function $f\left(x\right)=-x+b$, where $b$ is a constant, and find the following.

a. $f\left(f\left(0\right)\right)$

b. $f\left(f\left(2\right)\right)$

c. All inputs $x$ for which the final output is $x$, that is $f\left(f\left(x\right)\right)=x$.