a) \(\left(45x105-225\right)-\left(210+42x95\right)\)
\(=45x\left(100+5\right)-225-210+42x\left(100-5\right)\)
\(=4500+45x5-225-210+4200-42x5\)
\(=4500+4200+45x5-42x5-225-210\)
\(=8700+5x\left(45-42\right)-435\)
\(=8700+15-435=8280\)
a: =45*105-225-210-42*95
=45*(105-5)-42(95+5)
=100*3
=300
b: =47(105-5)-42(96+4)
=47*100-42*100
=5*100
=500
b) \(\left(47x105-235\right)-\left(168+42x96\right)\)
\(=47x\left(100+5\right)-235-168-42x\left(100-4\right)\)
\(=4700+235-235-168-4200-168\)
\(=4700-4200+235-235-168-168\)
\(=500\)
