The graph of a function $f(x)$ is given below. Evaluate the integrals geometrically in terms of area and properties of the definite integral. $($Assume each critical point's height is an integer.$)$

$($a$){\displaystyle \underset{0}{\overset{8}{}}}f(x)dx$

$$

$($b$){\displaystyle \underset{4}{\overset{12}{}}}f(x)dx$

$$

$($c$){\displaystyle \underset{2}{\overset{10}{}}}f(x)dx$

$$

Please help! Thnak you!!!