we know that lines that the products of lines that are perpendicular is equal to -1
so to find the slope
y+4x=9---->y=-4x+9--->the slope is -4
the line that is perpendicular to this line has a slope of (1/4) since -4*(1/4)=-1
we know that the line point formula is
(y-y1)=m(x-x1) where m is the slope
we were given the point (-4,8) therefore
y-8=(1/4)(x+4)
y-8=x/4+1
y=x/4+9