Parallel lines have the same gradient (same 'm' value in y=mx+c). Therefore m=3 for both equations; if they are parallel lines. The second equation needs to be rearranged for y to determine this. 3y-9x+5 = 0, 3y = 9x-5 y = 3x - 5/3 Therefore m=3 in the second equation, and the lines are parallel.