\(a,-81.46-81.55+81\)
\(=81.\left(-46\right)-81.55+81\)
\(=81.\left(-46-55+1\right)\)
\(=81.\left(-100\right)\)
\(=-8100\)
\(b,35.\left(17-5\right)-17.\left(35-5\right)\)
\(=35.17-35.5-17.35+17.5\)
\(=\left(35.17-17.35\right)-\left(35.5-17.5\right)\)
\(=35.\left(17-17\right)-5.\left(35-17\right)\)
\(=35.0-5.18\)
\(=0-90\)
\(=-90\)
Cách 2 : \(35.\left(17-5\right)-17.\left(35-5\right)\)
\(=35.12-17.30\)
\(=420-510\)
\(=-90\)
\(c,-125.6.\left(-8\right).\left(-50\right)\)
\(=\left(-125\right).\left(-8\right).6.\left(-50\right)\)
\(=1000.\left(-300\right)\)
\(=-300000\)