41.2*8.1+11*1.25+53.7*1.9
=41.2*8.1+11*1.25+(41.2+12.5)*1.9
=41.2*8.1+1.1*12.5+41.2*1.9+12.5*1.9
=(8.1+1.9)*41.2+(1.1+1.9)*12.5
=10*41.2+3*12.5
=412+37.5
=449.5