Determine whether the graph of two equations are perpendicular. X+2y=5, 2x+4y=8?

X+2y=5  2y=-x+5    y=-1/2x+5/2    k=-1/2
2x+4y=8    x+2y=4    y=-1/2x+2      k=-1/2
(-1/2)*(-1/2)=1/4
so the two equations are not perpendicular.