又九分之七减二又九分之二+(2又九分之七减一又十七分之九)七又九分之七减二又九分之二加(二又九分之七减一又十七分九)要最简便的

问题描述:

又九分之七减二又九分之二+(2又九分之七减一又十七分之九)
七又九分之七减二又九分之二加(二又九分之七减一又十七分九)
要最简便的

=7-2+2-1+(7/9-2/9+7/9-9/17)
=6+1+7/9-9/17
=7又38/153