a) 4045 : 5 + 451 * 75 - (729 - 642)
- $$729 - 642 = 87$$
- $$4045 : 5 = 809$$
- $$451 * 75 = 33825$$
- $$809 + 33825 = 34634$$
- $$34634 - 87 = 34547$$
Ответ: 34547.
б) 1027 - 428 + 307 * 280 - (60 005 - 5168)
- $$60 005 - 5168 = 54837$$
- $$307 * 280 = 85960$$
- $$1027 - 428 = 599$$
- $$599 + 85960 = 86559$$
- $$86559 - 54837 = 31722$$
Ответ: 31722.