General equation of a line: y=mx+b, being m=slope
As a first step to create the equation of the perpendicular line, you have to calcuate the slope, the slope of a perpendicular line is the ''negative reciprocal'' of the slope of the original line:
The slope of the original line is: 1/3, so the slope of the perpendicular line to this is: -3
Then, by the slope-point equation of a line:
Slope: -3, Point given: (-1, -4)
Y-Y0=-3(X-X0)
Y-(-4)=-3(X-(-1))
Y+4=-3(X+1)
Y+4=-3X-3
Y=-3X-7 ---> GENERAL EQUATION OF THE PERPENDICULAR LINE