I need help creating an expression to have 2 sets of numbers interact with each other.

I have to level graphs next to each other with a minimum of 0 and a max of 100 As the right graph goes up the left graph should go down with a value of both numbers always equalling 100.

I have an expression slider to move the right graph up and down from 0 - 100 and the numbers interact accordingly. Where I'm stuck right now is the only way I could get the left graph to be correct was to move it in the negative value. What can I add to the expression to remove the negative symbol?

Any help would be appreciated