41.2乘8.1加洞档猛纳桥蠢察11乘1.25加53.7乘1.9=41.2x8.1+11x1.25+(41.2+12.5)x1.9=41.2x8.1+11x1.25+41.2x1.9+12.5x1.9=41.2x(8.1+1.9)+11x1.25+1.25x19=41.2x10+1.25x(11+19)=412+1.25x30=412+37.5=449.5
