perpendicular lines have slopes that are negative reciprocals of each other, that is, if one slope is a/b, the other slope is -b/a
the given line 3x-4y=24, 4y=3x-24, y=3/4x-6 has a slope of 3/4, so the slope of the perpendicular line has a slope of -4/3
y=(-4/3)x+b, b can be any number.
