How to do operations that change a relation?

edit

For example, given a < b, we know that if we multiply both sides with -1, we will get -a > -b.

But in sage, if I try this:

var('a b')
exp=a>b
exp*-1

I get:

  −a>−b

The > did not get flip (the same also happens if we take the reciprocal).

Are the functions in Sage that can perform the multiplication with properly handle the inequality as well? Otherwise, what is the recommended way to do this manually?