2/9*3/8+0.375+7/9*37.5%=1/12+0.375+7/9*0.375=1/12+0.375(1+7/9)=1/12+3/4*16/9=/12+3/4=17/12
2/9x3/8+0.375+7/9x37.5% =2/9x3/8+7/9x3/8+3/8 =(2/9+7/9) x3/8+ 3/8=3/8+3/8=6/8=3/4
0.75 或者 3/4注意3/8=0.375 可运用简便算法
