`a) 21.(-29)+(-17).(-13)`
`=-609+221`
`=-388`
`b) (– 11)2.3 – [3 – (– 5)( – 4)]`
`= (– 11)2.3 – [3-20]`
`=(– 11)2.3 – (-17)`
`=(-22).3-(-17)`
`=(-66)-(-17)`
`=-49`
`c) (– 143):(– 13) – (– 5).(– 12)`
`=11-60`
`=-49`
`d)17 – {(– 32) – (–3) 3 – [5.(– 41) – 12:(– 4)0 ]+ 1571}`
`=17 – {(– 32) – (–3) 3 – [-205 – (-3).0 ]+ 1571}`
`=17 – {(– 32) – (–3) 3 – [-205 – 0 ]+ 1571}`
`=17 – {(– 32) – (–3) 3 – (-205)+ 1571}`
`=17 – {(-29). 3 – (-205)+ 1571}`
`=17 – {(-87) – (-205)+ 1571}`
`=17 – {118+ 1571}`
`=17 – 1689`
` =-1672`