intros w w' w''; make_fraction w ipattern:(p) ipattern:(q) ipattern:(Heq);
make_fraction w' ipattern:(p') ipattern:(q') ipattern:(Heq');
make_fraction w'' ipattern:(p'') ipattern:(q'') ipattern:(Heq'').
intros H; apply Qpositive_le'_to_Qpositive_le;
generalize (Qpositive_le_to_Qpositive_le' _ _ H);
clear H.
unfold Qpositive_le', Qpositive_mult in |- *; simpl in |- *; rewrite Heq;
rewrite Heq'; rewrite Heq''.
expand (S p * S p'') (S q * S q'') (S p * S p'' + S q * S q'') ipattern:(d)
ipattern:(p3) ipattern:(q3) ipattern:(Heq3) ipattern:(Heq1) ipattern:(Heq2).
expand (S p' * S p'') (S q' * S q'') (S p' * S p'' + S q' * S q'')
ipattern:(d') ipattern:(p4) ipattern:(q4) ipattern:(Heq4) ipattern:(Heq5)
ipattern:(Heq6).
intros Hle; apply mult_S_le_reg_l with d; rewrite (mult_comm (S p3));
repeat rewrite (mult_comm (S d)); repeat rewrite <- mult_assoc.
rewrite <- Heq1; rewrite <- Heq2.
apply mult_S_le_reg_l with d'; repeat rewrite mult_assoc;
repeat rewrite (mult_comm (S d')); rewrite <- Heq5;
rewrite <- Heq6.
replace (S q' * S q'' * S p * S p'') with (S q'' * S p'' * (S p * S q')).
replace (S p' * S p'' * S q * S q'') with (S q'' * S p'' * (S p' * S q)).
apply (fun m n p : nat => mult_le_compat_l p n m); exact Hle.
ring.
ring.
Qed.

Theorem Qpositive_plus_le :
forall w w' : Qpositive, Qpositive_le w (Qpositive_plus w w').