Пошаговое объяснение:
1. а) 54 – (129–46) = 54 - 129 + 46 = -29
б) 28 + (122 – 228) = 28 + 122 - 228 = -78
в) 23 – (–13+76) = 23 +13 - 76 = -40
2. а) (44–18) - (–21–18) = 44–18+21+18
44 - 18 + 21 + 18 = 44–18+21+18
65 = 65
б) -(–84–13)-(25–10) = 84+13–25+10
84+13-25+10) = 84+13–25+10
82=82
в) -(65+13)+( –11–115) = –65–13–11–115
-65-13–11–115 = –65–13–11–115
-204= -204
3. а) 25 + (x + 12) = 78
25+х+12=78
х=78-25-12
х=41
б) 126 –(–134 – a) = 115
126+134+а=115
а=115-126-134
а= 115-260
а= -145
в) – 405 – (28 + m) = - 267
-405-28-m= -267
-m= -267+405+28
-m= -267+433
-m= 166
m= -166
