Решение:
a) (421 - 287) * 8 = 134 * 8 = 1072
б) 27 * 75 - 34 * 43 = 2025 - 1462 = 563
в) 118 * 24 + 128 * 25 = 2832 + 3200 = 6032
г) 43 * 32 * 35 = 1376 * 35 = 48160
д) (427 - 389) * (56 + 105) = 38 * 161 = 6118
e) (2103 + 1937 - 3041) * 21 = (4040 - 3041) * 21 = 999 * 21 = 20979