=(4.4+3.4)×0.8=7.8×0.8=(8-0.2)×0.8=8×0.8-0.2×0.8=6.4-0.16=6.24
原式可化为:(4.4+3.4)x0.8=7.8x0.8=6.24
原式=0.8x(4.4+3.4)=0.8x7.8=0.8x7+0.8x0.8=5.6+0.64=6.24