Answer
a) $x=3$
b) $x-3=0$
Work Step by Step
a) The equation of a line in slope-intercept form is:
$$\begin{align*}y=mx+b,\end{align*}$$
where $m$ is the slope and $b$ in the $y$-intercept.
We are given:
$$\begin{align*}
&P(3,-2)\text{ belongs to the line}\\
&\text{The line is vertical}.
\end{align*}$$
Because the line is vertical, its equation is
$$\begin{align*}x=a,\text{ where }a\text{ constant}\end{align*}$$
We determine $a$ using the fact that the point $P$ belongs to the line:
$$\begin{align*}x=3.
\end{align*}$$
b) The equation of a line in general form is:
$$Ax+By+C=0.$$
Rewrite the equation $x=3$ in general form:
$$\begin{align*}
x-3&=0.
\end{align*}$$
c) Graph the line using the points $P$ and the $x$-intercept $(3,0)$: