48x0.56+52x0.56=0.56x(48+52)=0.56x100=56
48×0.56+52×0.56＝（48+52）×0.56＝100×0.56＝56
48*0.56+52*0.56=0.56*（48+52）乘法分配律简便=0.56*100=56
48×0.56＋52×0.56＝0.56×（48＋52）＝0.56×100＝56
