rewrite < H5.
rewrite < sym_times.
apply plus_to_minus.
-apply eq_plus_to_le ? ? ? H3.
apply H3.
apply le_times_r.
apply lt_to_le.
rewrite < H3.
rewrite < sym_times.
apply plus_to_minus.
-apply eq_plus_to_le ? ? ? H5.
apply H5.
apply le_times_r.
apply lt_to_le.