a) 14 * 4 + 16 * 4 = 4 * (14 + 16) = 4 * 30 = 120
б) 18 * 3 + 12 * 3 = 3 * (18 + 12) = 3 * 30 = 90
в) 13 * 7 + 7 * 17 = 7 * (13 + 17) = 7 * 30 = 210
г) 25 * 5 + 5 * 5 = 5 * (25 + 5) = 5 * 30 = 150
a) 68 * 18 - 68 * 8 = 68 * (18 - 8) = 68 * 10 = 680
б) 74 * 16 - 74 * 15 = 74 * (16 - 15) = 74 * 1 = 74
в) 34 * 52 - 31 * 52 = 52 * (34 - 31) = 52 * 3 = 156
г) 99 * 15 - 96 * 15 = 15 * (99 - 96) = 15 * 3 = 45