Вправи 501 - 600 » 543-544

543. 28 – 4 + 2 = 2; 28 + 4 – 2 = 30 або 28 + 4 : 2 = 30; 28 + 4 • 2 = 36. 544. 62 – 60 = 502; 279 – 9 = 270; 324 – 300 = 24; 742 – 42 = 700.