Answer
$y=3$
Work Step by Step
$f(0)=3$ can be written as $(0,3)$ and $f(-6)=3$ as $(-6,3)$.
Slope $m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}=\frac{3-3}{-6-0}=0$
Because the line crosses the y-axis at $(0,3)$,
Y-intercept $b=3$.
Equation of line in the slope-intercept form is
$y=mx+b$.
Substituting the values of $m$ and $b$, we get an equation of line as
$y=0x+3$ or $y=3$
