intuition.
eapply leRat_trans.
eapply eqRat_impl_leRat.
apply ratAdd_0_r.
eapply leRat_trans.
eapply ratAdd_leRat_compat.
apply leRat_refl.
apply rat0_le_all.
eauto.
Qed.

Lemma posnatMult_1_r : forall p,
posnatToNat (posnatMult p (pos 1)) = posnatToNat p.