а) 12 * 23 + 12 * 77 = 12 * (23 + 77) = 12 * 100 = 1200
б) 51 * 18 - 18 * 21 = 18 * ( 51 - 21) = 18 * 30 = 540
а) 12 * 23 + 12 * 77 = 12 * (23 + 77) = 12 * 100 = 1200
б) 51 * 18 - 18 * 21 = 18 * ( 51 - 21) = 18 * 30 = 540