-4x > 20

This is why, when we've got something like

3x + 2 < x - 4

I always tell you ditch the smaller x guy first!  See what happens if we start by ditching the 3x instead:

3x + 2 < x - 4, subtract 3x from both sides which gives 2 < -2x - 4, add 4 to both sides which gives 6 < -2x (Danger!)


Now, we'd have to divide by a negative... And, if we forget to flip the sign, we're dead.  Trust me, I've graded thousands of these problems and even the best students forget to flip signs when they are nervous.  It's best to avoid it if you can - just one less thing to worry about!