`a) 6/18 + 5/8 : 5 - 3/16 . (-2)^2`
`= 6/18 + 1/8 - 3/16 . 4`
`=1/3 + 1/8 - 3/4`
`=8/24 + 3/24 - 18/24`
`=-7/24`
``
`b) 6/7 + 5/8 : 5 - 3/16 . (-4)^2`
`= 6/7 + 1/8- 3/16 . 16`
`=6/7 + 1/8 - 3`
`=-113/56`
``
`c) (-7)/15 . 5/8 . 15/(-7) . (-16)`
`= ((-7)/15 . 15/(-7)) . ( 5/8 . (-16))`
`= 1 . (-10)`
`= (-10)`
``
`d) 1 13/15 . 0,75 - ( 11/20 + 25%) : 7/5`
`=28/15 . 3/4 - ( 11/20 + 1/4) . 5/7`
`= 7/5 - 4/5 . 5/7`
`= 7/5 - 4/7`
`= 29/35`
``
`e) ( 1.6 + 1/3) : 5 4/5 - 4/81 . (-3)^2`
`= 29/15 : 29/5 - 4/81 . 9`
`= 1/3 - 4/9`
`= -1/9`