25✘0.49+0.25✘51
=25✘0.49+25✘0.51............根据积不变的规律改写
=25×(0.49+0.51)............乘法的分配律
=25×1
=25
25×0.49+0.25×51=0.25×49+0.25×51=0.25×(49+51)=0.25×100=25
25*0.49+0.25*51=0.25*49+0.25*51=0.25*(49+51)=0.25*100=25