Answer
$ a.\quad$ see graph below
$b.\displaystyle \quad m=-\frac{3}{4}$
Work Step by Step
a.
Find the intercepts with the axes
$\left[\begin{array}{lll}
3x+0=12 & ... & 0+4y=12\\
x=4 & & y=3\\
(4,0) & & (0,3)
\end{array}\right]$
Plot the intercepts and join with straight line
b.
slope=$\displaystyle \frac{\text{change in y}}{\text{change in x}}$
Using the two points we found in part a,
$m=\displaystyle \frac{3-0}{0-4}=-\frac{3}{4}$
Any line parallel to this line has the same slope.
