Додаткові вправи » 2

х + 280 = 370 х = 370 – 280 х = 370 – 270 – 10 х = 90__________ 90 + 280 = 370 370 = 370 450 – х = 270 х = 450 – 270 х = 450 – 250 – 20 х = 200 – 20 х = 180_________ 450 – 180 = 270 450 – 150 – 30 = 270 270 = 270 х – 180 = 450 х = 450 + 180 х = 450 + 150 + 30 х = 600 + 30 х = 630____________ 630 – 180 = 450 630 – 130 – 50 = 450 450 = 450