Найдите значение выражений 1) (2/7 + (15/28)) + ( 0,67 + (-6,5)) 2) (-0,68 + (-7,9 ))+ (-5/9+11/36) 3) (-2 целых 1/7 - 5 целых 5/14) - (15,38+4,6)

1) (23/28) + (-5.83) = 23/28 - 583/100 = (230 - 1632.4) / 280 = -(1402.4 / 280) =  - (701.2 / 140) = (350.6 / 70) = (35.06 / 7)
2) (-8.58) + (-9/36) = -8.58 - 0.25 = -8.83.
3) (15/7 - 70/14) = -(20/7) - (19.98) = - 20/7 - 1998/100 = (-1000 - 6993 / 350) = 7993/350.