负六十五又十五分之十三除以十三
=-(65+13/15)×1/13
=-(65×1/13+13/15×1/13)
=-(5+1/15)
=-5又15分之1
(-2△7)△4=[-1/2÷(-7/2)]△4=1/7△4=7÷(-2)=-7/2