We need to put these equations into y=mx+b format. 5x-3y=-6 -3y=-5x-6. (take 5x from both sides) y=5/3 x +2 ( divide both sides by -3) The slope is 5/3
3x+5y=-20 5y= -3x -20 (subtract 3x from both sides) y=-3/5x -4 (divide both sides by 5) The slope is -3/5
The slopes of perpendicular lines are the opposite (+/-) reciprocal. We have 5/3 and -3/5. This shows they are perpendicular.
