Invert chop?

Im trying to control a LEVEL top from a keyboard input. 3 movies correctly fade in from 0 to 1 with a FILTER chop, another movie conversely needs to fade in when the others fade out so Im hoping to ‘invert’ this process, i.e. from 1 to 0. Any suggestions how to go about this would be much appreciated!

Use Math CHOP’s Range From and Range To parameters to do this.

Thanks Malcolm!