Find the slopes by making y the subject of each equation then use the x coefficient as the slope.
a) 7/4
b) -4/7
c) 4/7
d) -4/7
The equation 4y-7x=5, y=7x/4+5/4 has slope 7/4 so its perpendicular has to be -4/7, so the answer would appear to be b and d.