(1)9×9-9÷9=81-1=80
(2)9×{9-(9/9)/9}=9×80/9=80
(3){9-〔9÷(9×9)〕}×9
={9-〔9÷81〕}×9
={9-1/9}×9
=80/9×9
=80
(4)(9-9÷9÷9)×9=80
(5)(9×9×9-9)÷9=80
(1)9×9-9÷9=81-1=80
(2)9×{9-(9/9)/9}=9×80/9=80
(3){9-〔9÷(9×9)〕}×9
={9-〔9÷81〕}×9
={9-1/9}×9
=80/9×9
=80
(4)(9-9÷9÷9)×9=80
(5)(9×9×9-9)÷9=80