Пошаговое объяснение:
1.
1) - 2,1•3,8=-7,98
2) - 1• (-2) = 2
3) - 14,16: (-0,6) = 23,6
4) - 18,36:18=-1,02
2.
1) - 1,6x• (-5y) = 8xy
2) - 7a-9b+a+11b=-6a+2b
3) a - (a-8) + (12+a) = a-a+8+12+a=a+20
4) - 3 (c-5) + 6 (c+3) = - 3c+15+6c+18=3c+
33
3.
(-4,16 - (-2,56)) : 3,2-1,2• (-0,6) = - 1,6:3,2+
0,72=-0,5+0,72=0,22
4.
-2 (2,7x-1) - (6-3,4x) + 8 (0,4x-2) = - 5,4x+2
-6+3,4x+3,2x-16=1,2x-20
x=-1
1,2• (-1) - 20=-1,2-20=-21,2
5.
eсли 2 х-у=-8
у=2 х+8
-0,8x - (0,6x-0,7y) = - 0,8x-0,6x+0,7y=
-1,4x+0,7y=-1,4x+0,7• (2x+8) = - 1,4x+1,4x+5,6=5,6
1000, 993, 986, 979, 972, 965, 958, 951, 944, 937, 930, 923, 916, 909, 902, 895, 888, 881, 874, 867, 860, 853, 846, 839, 832, 825, 818, 811, 804, 797, 790, 783, 776, 769, 762, 755, 748, 741, 734, 727, 720, 713, 706, 699, 692, 685, 678, 671, 664, 657, 650, 643, 636, 629, 622, 615, 608, 601, 594, 587, 580, 573, 566, 559, 552, 545, 538, 531, 524, 517, 510, 503, 496, 489, 482, 475, 468, 461, 454, 447, 440, 433, 426, 419, 412, 405, 398, 391, 384, 377, 370, 363, 356, 349, 342, 335, 328, 321, 314, 307, 300, 293, 286, 279, 272, 265, 258, 251, 244, 237, 230, 223, 216, 209, 202, 195, 188, 181, 174, 167, 160, 153, 146, 139, 132, 125, 118, 111, 104, 97, 90, 83, 76, 69, 62, 55, 48, 41, 34, 27, 20, 13, 6,-1 (только так)
2)410+350=760(км)-за два дня
3)950-760=190(км)-за 3-й день