>>26
訂正。ガラケーで入力大変。

(誤)
apply Z.mul_sub_distr_l.
omega.
symmetry.
apply Z.mul_sub_distr_r.
Qed.

(正)
apply Z.mul_sub_distr_l.
omega.
omega.
symmetry.
apply Z.mul_sub_distr_r.
Qed.