35*14-70+30怎樣簡便怎樣算?

35*14-70+30怎樣簡便怎樣算?


=70*7-40
=490-40
=450



(-270)*0.25+0.25*21.5+(-8.5)*(-0.25)=?


(-270)*0.25+0.25*21.5+(-8.5)*(-0.25)
=0.25x(-270+21.5+8.5)
=0.25x-240
=0.25x4x-60
=-60



(21.5-21)*25*0.5+25*0.4等於多少


(21.5-21)*25*0.5+25*0.4等於多少
= 0.5 x 25 x 0.5 + 25 x0.4
= 25 x 0.25 +25 x 0.4
= 25 x(0.25+0.4)
= 25 x 0.65
= 65 x 0.25
= 65÷4
= 16.25