Номер 150

Question

x + 460 = 660;
x = 660 – 460;
x = 200;
200 + 460 = 660;
660 = 660;

2 · x + 460 = 600;
2x = 600 – 460;
2x = 140;
x = 140 : 2;
x = 70;
2 · 70 + 460 = 600;
600 = 600;

x – 380 = 240;
x – 240 + 380;
x = 620;
620 – 380 = 240;
240 = 240;

x – (120 + 260) = 240;
x – 380 = 240;
x = 240 + 380;
x = 620;
620 – (120 + 260) = 240;
240 = 240;

x : 40 = 640;
x = 640 · 40;
x = 25600;
25600 : 40 = 640;
640 = 640;

820 : x = 20;
x = 820 : 20;
x = 41;
820 : 41 = 20;
20 = 20.