`a.`
`(-2020)-(234-2020)`
` =-2020 - 234 + 2020`
`= [(-2020) + 2020 ] - 234`
` = 0 - 234`
` = -234`
`b.`
`(-8).(-12).(-125)`
`=[(-125).(-8)] . (-12)`
` =1000 . (-12)`
` = -12000`
`c.`
`19.(-13)+17.(-19)`
`=19. ( -13) + ( -17) . 19`
` = 19. [(-13) +( -17) ]`
` = 19 . (- 30 )`
`= - 570`
`d.`
`(-5) ².(-3) ³. 2 ³`
`= 25 . ( - 27 ) . 8`
` = (25.8) .(- 27 )`
` =200 . ( -27)`
` = -5400`