2.3X0.48+0.48X8.7-0.12X4=2.3X0.48+0.48X8.7-0.48=0.48X(2.3+8.7-1)=0.48X(11-1)=0.48X10=4.8
=0.48×(2.3+8.7-1)=0.48×10=4.8
如图