=0.84×1.2+0.84×8.8=0.84×(1.2+8.8)=0.84×10=8.4
简便算法解题0.84×1.2+8.4×0.880.84×1.2+8.4×0.88=0.84*1.2+0.84+8.8=0.84*(1.2+8.8)=0.84*10=8.4