Answer
a) $40$
b) $f(2)=0$.
Work Step by Step
a) $f(0)$ is the value of the function at $t=0$, which according to the graph, is $40$, hence $f(0)=40.$
b) $f(t)=0$ if the value of the function is $0$ at $t$. According to the graph, the value of the function is $0$ at $t=2$, hence $f(2)=0$.
