(-2/3)-( )=-1/3 (-15)-()=-100 (-2/3)+()=-1/3

问题描述:

(-2/3)-( )=-1/3 (-15)-()=-100 (-2/3)+()=-1/3

(-2/3)-(-1/3 )=-1/3 (-15)-(+85)=-100 (-2/3)+(1/3)=-1/3