Номер 14

230 + x = 840;
x = 840 – 230;
x = 610;

x – 320 = 460;
x = 460 + 320;
x = 780.

x + 540 = 870;
x = 870 – 540;
x = 330;

950 – x = 370;
x = 950 – 370;
x = 580.

640 – x = 380;
x = 640 – 380;
x = 260;

460 + x = 520;
x = 520 – 460;
x = 60.