15/56+ (-55/84) -28/75+32/125 17/48+(-25/72) 3/4+(-5/6)+(-7/9)+11/18 5/14+(-10/21)+17/28+(-4/7) вот этот знак «/» обозначает дробь

- 15/56 + (-55/84) = - (45/168 + 110/168) = - 155/168
- 28/75 + 32/125 = - 140/375 + 96/375 = - 44/375
17/48 + (-25/72) = 51/144 - 50/144 = 1/144
3/4 + (-5/6) + (-7/9) + 11/18 = 27/36 - 30/36 - 28/36 + 22/36 = - 9/36 = - 1/4
5/14 + (-10/21) + 17/28 + (-4/7) = 30/84 - 40/84 + 51/84 - 48/84 = - 7/84 = - 1/12