Пошаговое объяснение:
1) 2,5 - 2. 1/3 = 2. 5/10 - 2. 1/3 = 2. 15/30 - 2. 10/30 = 5/30 = 1/6
2) 1/6 * (-5. 1/7) = 1/6 * (-36/7) = 1/1 * (-6/7) = -6/7
3) 1. 1/3 : (-5,6) = 4/3 : (-5. 6/10) = 4/3 : (-56/10) = 4/3 * (-10/56) = 1/3 * (-10/14) = -10/42 = -5/21
4) -6/7 + (-5/21) = -6/7 - 5/21 = -18/21 - 5/21 = -23/21 = -1. 2/21
ответ: -1. 2/21
