`a)82/11 - (8/5 + 27/11)`
`=82/11 - 8/5 - 27/11`
`=(82/11 - 27/11)- 8/5`
`=55/11 - 8/5`
`= 5 - 8/5`
`= 17/5`
`b)-3/8 . 9/14 + 5/14 . -3/8 + 1,25`
`=-3/8.(9/14 + 5/14) + 1,25`
`=-3/8.1 + 1,25`
`=-3/8 +1+0,25`
`=5/8 + 1/4`
`=7/8`
`c)23/15 . 0,75 -(11/20 + 25%):(-2/5)^2`
`=23/20 - 11/20 - 25%:4/25`
`=3/5 - 1/4 : 4/25`
`=3/5 - 25/16`
`=-77/80`