`b, (0,125) . (-4,7) . (-2)^3`

`=0,125 . (-4,7) .(-8)`

`=0,125 . 4,7 . 8`

`=(0,125 . 8) . 4,7`

`=1 . 4,7`

`=4,7`

`c, 12 1/4 : 4/3 +4 1/4 : (-4/3)`

`=49/4 . 3/4 + 17/4 . (-3/4)`

`=49/4 . 3/4-17/4 . 3/4`

`=(49/4-17/4) . 3/4`

`=8 . 3/4`

`=6`

`d, 7 . 2^3 -5{[10,51 +4 . (3/4-2/5)^2]-2021^0}`

`=7 . 8 -5{[10,51 +4 . (7/20)^2]-1}`

`=56 - 5 {[10,51 +4 . 49/400]-1}`

`=56-5{[1051/100+49/100]-1}`

`=56-5 . (11 -1)`

`=56-5 . 10`

`=56-50`

`=6`