## Calculus (3rd Edition)

$$y=5.$$
Since the line is horizontal, its slope is $0$; hence the line has the equation $$y=(0)x+c=c.$$ To find $c$, we make use of the fact that the line passes through $(-3,5)$: $$5= c\Longrightarrow c=5$$ Hence the equation of the line is $$y=5.$$