The given equation is:
$$ \color{blue}{ y = 3 x + 12 } $$To draw the graph we will find y-intercept and x-intecept.
To find y - intercept we substitute $ \color{blue}{x = 0} $:
$$ \begin{aligned} y &= 3 x + 12 \\y &= 3 \cdot \color{blue}{0} + 12\\y &= 12 \\\end{aligned} $$To find x - intercept we substitute $ \color{blue}{y = 0}$:
$$ \begin{aligned} y &= 3 x + 12 \\\color{blue}{0} &= 3 x + 12\\x &= -4\end{aligned} $$So, the graph of the equation is: