A function $f$ has a derivative $f^{\text{'}}$ whose graph is shown below. Use the graph of $f^{\text{'}}$ to answer questions about $f.$

$($a$)$ For what values of $x$ is $f$ increasing? $($Enter your answer using interval notation.$)$

$$

For what values of $x$ is $f$ decreasing? $($Enter your answer using interval notation.$)$

$$

$($b$)$ For what values of $x$ does $f$ have either a local maximum or a local minimum? $($Enter your answers as a comma$-$separated lise$)x=$