\(A=19.95+19.95-19.30\)
\(=19\left(95.2-30\right)\)
\(=19.160=3040\)
\(B=-8.25.\left(-2\right).4.\left(-5\right).125\)
\(=\left(25.4\right)\left[\left(-2\right)\left(-5\right)\right].8.125\)
\(=100.10.8.125\)
\(=1000.1000=1000000\)
\(C=\left(-150\right)-\left\{125.8-11.\left[49-5.8+8\left(1121-121\right)\right]\right\}\)
\(=-150-125.8+11.\left[49-40+8.1000\right]\)
\(=-150-1000+11.8009\)
\(=-1150+88099=86949.\)