а) -3/5-9/10, в) -2/3-5/6, д) 2/5-13/50

- 3/5 - 9/10 = - 6/10 - 9/10 = - 15/10 = - 1,5 - 2/3 - 5/6 = - 4/6 - 5/6 = - 9/6 = - 1,5 2/5 - 13/50 = 20/50 - 13/50 = 7/50