3.75x2.6+3.75x4.7+6.25x7.3=3.75x（2.6+4.7）+6.25x7.3中的6.25=10-3.75带入式中=3.75x（2.6+4.7）+（10-3.75）x7.3=3.75x7.3-3.75x7.3+10x7.3=0+10x7.3=0+73=73
写在下面图片上的
