a,
f(-1) = |1 - (-1)| + 2 = 4
f(\(\dfrac{3}{2}\)) = \(\left|1-\dfrac{3}{2}\right|+2=\dfrac{5}{2}\)
b,
f(x) = 5
<=> |1-x| + 2 = 5
<=> |1-x| = 3
<=> \(\left[{}\begin{matrix}1-x=3\\1-x=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=4\end{matrix}\right.\)