5/12 - 3/(-16) - 3/4
= 20/48 + 9/48 - 36/48
= -7/48
--------
-1/12 - (1 + 1/3)
= -1/12 - (3/3 + 1/3)
= -1/12 - 4/3
= -1/12 -16/12
= -17/12
--------
17/8 : [27/8 + (-11/2)]
= 17/8 : (27/8 - 44/8)
= 17/8 : (-17/8)
= -1
--------
28/15 . (1/4)² . 3 + (8/15 - 69/60 . 5/23)
= 28/15 . 1/16 . 3 + (8/15 - 1/4)
= 7/20 + (32/60 - 15/60)
= 7/20 + 17/60
= 21/60 + 17/60
= 19/30