`a) 3/8 - 4/5 - (-17/40)`

`= 15/40 - 32/40 + 17/40`

`= (15 - 32 + 17)/40`

`= 0`

`b) 3/4 - 16/32 + 4/(-3)`

`= 3/4 - 1/2 - 4/3`

`= 3/4 - 2/4 - 4/3`

`= 1/4 - 4/3`

`= -13/12`

`c) -4/7 + 3/3 . (-9/4)`

`= -4/7 + 1 . (-9/4)`

`= -4/7 + (-9/4)`

`= -79/28`

`d) 8 2/7 - 3 4/9 + 4 2/7`

`= (8 2/7 + 4 2/7) - 3 4/9`

`= 88/7 - 3 4/9`

`= 88/7 - 31/9 = 575/63`

`e) (2/3 - 1 1/2) : 4/3 + 1/2`

`= (2/3 - 3/2) : 4/3 + 1/2`

`= -5/6 . 3/4 + 1/2`

`= -5/8 + 1/2 = -1/8`

`f) -5/13 + 2/5 + (-8/13) + 3/5 - 3/7`

`= (-5/13 - 8/13) + (2/5 + 3/5) - 3/7`

`= -1 + 1 - 3/7`

`= -3/7`