Do you mean "perpendicular to k"? We have no line c there so I'm going with line k. First we need the slope of line k. Fitting those values into the slope formula we have [tex]m= \frac{12-(-6)}{-1-(-3)} = \frac{18}{2} =9[/tex]. So the slope of k is 9. The slope of a line perpendicular to k has the opposite sign and the fraction is flipped. The perpendicular slope then is -1/9.
