I was messing with shaders earlier. I connected the facing ratio attribute of a samplerInfo node to the reflectivity of a blinn shader. Now I want to invert the reflectivity i.e. when the facing ratio is 1 I want reflectivity to be 0 and viceversa.

I know I probably have to use the graph editor for this. But I'm not sure how to do it.

Can you please help me out?

Thanks.