(-121.4)+(-78.5)-(-8又2分之1)-(-121.4)

问题描述:

(-121.4)+(-78.5)-(-8又2分之1)-(-121.4)

(-121.4)+(-78.5)-(-8又2分之1)-(-121.4)
=(-121.4)-(-121.4)+(-78.5)-(-8又2分之1)
=-121.4+121.4+(-78.5)-(-8又2分之1)
=(-78.5)-(-8又2分之1)
=-78.5+8.5
=-70