Proof of proveit.numbers.division.cancel_negations theorem

import proveit
theory = proveit.Theory() # the theorem's theory

%proving cancel_negations

With these allowed/disallowed theorem/theory presumptions (e.g., to avoid circular dependencies), we begin our proof of
cancel_negations:
(see dependencies)

cancel_negations may now be readily provable (assuming required theorems are usable).  Simply execute "%qed".