-0.5-3又4分之1+2.75-(+7又2分之1)=-0.5-3.25+2.75-7.5=-(0.5+3.25-2.75+7.5)=-(3.75-2.75+7.5)=-(1+7.5)=-8.5祝你开心
-0.5-3又4分之1+2.75-(+7又2分之1)=-0.5-3.25+2.75-7.5=(2.75-3.25)-(0.5+7.5)=-0.5-8=-8.5