(x-80):40=640
x-80=640*40
x-80=25600
x=25600+80
x=25680
(x-80)×40=640
40x-3200=640
40x=640+3200
40x=3840
х=96
x-80=640:40
x-80=96
x=176
x-80=640×40
(x-80):40=640
x-80=640*40
x-80=25600
x=25600+80
x=25680
(x-80)×40=640
40x-3200=640
40x=640+3200
40x=3840
х=96
x-80=640:40
x-80=96
x=176
x-80=640×40
x-80=25600
x=25680