the slope intercept form is y=mx+b where b is the y-intercept and m is the slope
y=-3x+b
substituting in the point (-4,-6)
-6=12+b
b=-18
so our equation is y=-3x-18
we can also solve by using the slope point formula
y-y1=m(x-x1)
y+6=-3(x+4)
y+6=-3x-12
y=-3x-18 which is the same as our first answer