proposition: Lemma eqR_divl_mulr z x y : z != 0 -> (x = y / z) <-> (x * z = y).
proof: Proof. by move=> z0; split; move/esym/eqR_divr_mulr => /(_ z0) ->. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum) Reals mathcomp(lra) mathcomp(Rstruct)