Determine Whether The Graphs Of The Equations Are Perpendicular 7x-4y=5 And 7y-4x=2?

Yes they are perpendicular because the graph is perpendicular when the slopes are the reciprocal of each other  ex. Slope= 2 slope= -1/2 (flip it and change the sign)

these graphs are perpendicular because the slope is the reciprocal  
7y-4x=4   slope = 4/7
7x-4y=5   slope = -7/4