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

these graphs are perpendicular because the slope is the reciprocal

7y-4x=4 slope = 4/7

7x-4y=5 slope = -7/4