1.(-2 3/14)+(-1 5/7)-(-19/21) = - 31/14 - 12/7 + 19/21 = - 93/42 - 72/42 + 38/42 = - 165/42 +38/42 = - 127/42 = - 3ц 1/42
2.(2 3/14-1 5/7+19/21) = 31/14 - 12/7 + 19/21 = 93/42 - 72/42 + 38/42 = 59/42 = 1ц 17/42
3.-(-4):(-1 1/3) = 4 : ( - 4/3) = 4 * ( - 3/4) = -3
4.(-3 1/9)+(1 5/12)-(-17/18) = - 28/9 + 17/12 + 17/18 = - 224/72 + 102/72 + 68/72 = - 54/72
5. (3 1/9-1 5/12+17/18) = 28/9 - 17/12 +17/18 = 224/72 - 102/72 + 68/72 = 190/72 = 95/36 = 2ц 23/36
6.-(-7):(-1 1/6) = 7 : ( - 7/6) = 7 * ( - 6/7) = -6