原式=41.2×8.1+11×9.25+53.7×1.9=41.2×8.1+11×9.25+（41.2+12.5）×1.9=41.2×（8.1+1.9）+11×9.25+12.5×1.9=41.2×10+11×9.25+19×1.25=412+11×8+（11+19）×1.25=412+88+30×1.25=500+37.5=537.5
。
