Cloud speed control

I’m trying to use a slider widget to control the cloud speed.

The setup below does work, but I have a little math problem it is clearly related to the float node if i am correct.
At the moment like I said the slider does work, but I can’t figure out how making it work like I do.

This is what I’m trying to do…

When the slider is down and I don’t use the slider, the cloud should move at regular speed, then when I slide the slider up the cloud should fast forward speed then when I hit the top of the slider these clouds should return at the regular speed and reverse if I use again the slider down.