If the lines are perpendicular their slopes are negative and reciprocal so the slope of the new line is 4/3
The equation of a line when we now the slope m=4/3 and a point (x=9, y=12) is
y-12 =4/3 (x-9) so is y= (4/3) x -(4•9/3)+12;
y= (4/3)x -12+12 so is y=(4/3)x +0