原式=(2.5+0.25)X0.4+2.75X0.6=2.75X0.4+2.75╳0.6=2.75(0.4+0.6)=2.75X1=2.75。或者原式=(2.5+0.25)Ⅹ0.4+(2.75)Ⅹ(1一0.4)=2.5X0.4+0.25Ⅹ0.4+2.75X1-(3-0.25)X0.4=1+0.1+2.75-1.2+0.1=2.75
(2.5+0.25)×0.4+2.75×0.6
=2.75×0.4+2.75×0.6
=2.75×(0.4+0.6)
=2.75×1
=2.75
(2.5+0.25)×0.4+2.75×0.6=2.75×0.4+2.75×0.6=2.75×(0.4+0.6)=2.75