400-х=170 х-80=90*7 400-х=270 х: 6=56+44 х: 6=156+44

400 - х = 170;

-х = 170 - 400;

-х = - 230;

-х * (-1) = - 230 * (-1);

х = 230;

400 - 230 = 170;

170 = 170.

х - 80 = 90 * 7;

х - 80 = 630;

х = 630 + 80;

х = 710;

710 - 80 = 630;

630 = 630.

400 - х = 270;

-х = 270 - 400;

-х = - 130;

х = 130;

400 - 130 = 270;

270 = 270.

х: 6 = 56 + 44;

х: 6 = 100;

х = 100 * 6;

х = 600;

600 : 6 = 56 + 44;

100 = 100.

х: 6 = 156 + 44;

х: 6 = 200;

х = 200 * 6;

х = 1200;

1200 : 6 = 156 + 44;

200 = 200.