[tex]m=\dfrac{y_2-y_1}{x_2-x_1}\\\\m=\dfrac{1-(-3)}{12-(-4)}=\dfrac{4}{16}=\dfrac{1}{4}[/tex]
Correct equation of the line is
[tex]y-1=\dfrac{1}{4}(x-12)[/tex]
The standard form is: Ax + By = C.
[tex]y-1=\dfrac{1}{4}(x-12)\qquad|\text{use distributive property}\\\\y-1=\dfrac{1}{4}x-3\qquad|\text{multiply both sides by 4}\\\\4y-4=x-12\qquad|\text{add 12 to both sides}\\\\4y+8=x\qquad|\text{subtract 4y from both sides}\\\\8=x-4y[/tex]