а) 81 308 – 308 * (8856 – 8649) + 54 600 : 6
$$8856 - 8649 = 207$$
$$308 \cdot 207 = 63756$$
$$54600 : 6 = 9100$$
$$81308 - 63756 = 17552$$
$$17552 + 9100 = 26652$$
Ответ: 26652
б) (52 * 390 – 8765 – 4098) * (1228 : 4 - 207)
$$52 \cdot 390 = 20280$$
$$20280 - 8765 = 11515$$
$$11515 - 4098 = 7417$$
$$1228 : 4 = 307$$
$$307 - 207 = 100$$
$$7417 \cdot 100 = 741700$$
Ответ: 741700