a)20-(-125).(-5).(-8) \(=20.\left(-5\right).1000=\left(-100\right).1000=-100000\)
b)2.11.(-8) \(=\left(-16\right).11=-176\)
c)123.25-75.(-12300) \(=123.\left(25+7500\right)=123.7525=925575\)
d)24.(16-5)-16.(24-5) \(=24.16-24.5-16.24+16.5=5.\left(-24+16\right)=5.\left(-8\right)=-40\)
e)29.(19-13)-19.(29-13) \(=29.19-29.13-19.29+19.13=13.\left(-29+19\right)=13.\left(-10\right)=-130\)
f)31.(-18)+31.(-81)-31 \(=31.\left(-18-81-1\right)=31.\left(-100\right)=-3100\)