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