(`12/32`+`5/-20`-`10/34`) 4`1/2`:(2/5-3`3/4`).(`-1/2`)^2

`(12/32+ -5/20 – 10/34)`

`= 3/8 – 1/4 – 5/17`

`= 51/136 – 34/136 – 40/136`
`= (51 – 34 – 40)/136`

`=-23/136`

`4 1/2 : (2/5 – 3 3/4). (-1/2)^2`

`= 9/2 : (2/5 – 15/4). 1/4`
`= 9/2 : (8/20 – 75/20). 1/4`

`= 9/2 : -67/20 . 1/4`
`= 9/2. -20/67. 1/4`

`= -90/67. 1 /4`

`= -45/134`