Answer
$a.$
A line parallel to the given line has slope $m=-\displaystyle \frac{2}{5}.$
$b.$
A line perpendicular to the given line has slope $m=\displaystyle \frac{5}{2}$
Work Step by Step
If two nonvertical lines are parallel, then they have the same slope.
If two nonvertical lines are perpendicular, then the product of their slopes is -1.
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Reading the slope from $y=mx+b$
$y= -\displaystyle \frac{2}{5}x-1$: $\quad$ The given line has slope $m=-\displaystyle \frac{2}{5}$.
$-\displaystyle \frac{2}{5}\cdot(\frac{5}{2})=-1$
$a.$
A line parallel to the given line has slope $m=-\displaystyle \frac{2}{5}.$
$b.$
A line perpendicular to the given line has slope $m=\displaystyle \frac{5}{2}$
