`a) 3/4 + 1,2-2 1/5 + 1`
`= 3/4+6/5-11/5+1`
`=15/20+24/20-44/20+20/20`
`= 3/4`
`b) |-7/9|+(-1/3)^2-(-2016)^0`
`= 7/9+1/9+1`
`= 17/9`
`c) 5/4:0,125-(2 1/2-0,8).5/2`
`= 5/4 . 8/1-(5/2-4/5) . 5/2`
`= 5/2-(25/10-8/10) . 5/2`
`= 5/2-17/10 . 5/2`
`= 5/2 - 17/4`
`=10/4-17/4`
`=-7/4`
`d) 0,75-38/90:(-4/5+2,5 . 4/3)`
`= 3/4-19/45:(-4/5+5/2 . 4/3)`
`= 3/4-19/45:(-4/5+10/3)`
`= 3/4-19/45:(-12/15+50/15)`
`= 3/4-19/45:38/15`
`= 3/4-19/45 . 15/38`
`= 3/4-19/114`
`= 171/228-38/228`
`= 133/228`