Apply df_sub__df_neg__df_div__df_nn__df_2__df_3__df_4__df_5__df_6__df_7__df_8__df_9__df_10OLD__df_n0__df_xnn0__df_z__df_dec__df_uz with
wceq cuz (cmpt (λ x0 . cz) (λ x0 . crab (λ x1 . wbr (cv x0) (cv x1) cle) (λ x1 . cz))).
The subproof is completed by applying H17.