The perpendicular line will have the x and y coefficients swapped and one of them negated. We can write the desired line as 9(x -6) -3(y -4) = 0 where the coordinates of the point of interest are (6, 4). Dividing by 3, this is 3(x -6) -(y -4) = 0 3x -y = 14
An equation for the line of interest is ... 3x -y = 14