Reverse coefficients at x and y and change the sign one time.

    (It is the way how to construct the equation of perpendicular line).


You will get the equation

    8x - 6y = c.   (1)

Now find the constant "c" under the condition that the coordinates of the "through" point satisfy the equation (1).


Simply substitute x = 4 and y = 9 into this equation (1) and find

c = 8*4 - 6*9 = 32 - 54 = -22.


Answer. The equation is 8x - 6y = -22.