Question 847666
Lines that intersect have only one solution.
Lines that are perpendicular intersect.
So one way is to write an equation that is perpendicular.
Lines that are perpendicular have slopes that multiply to -1

9x + 3y =-6
is the same line as 
y = -3 x-2 with slope
-3
1/3 would be the slope of a line perpendicular.
y =  x/3-2 or y = 1/3*x-2