2×(1-1又7分之1)+1又7分之3×13+(-1又7分之3)×6-16×(1又7分之3)
=2×(-7分之1)+1又7分之3×(13-6-16)
=-2/7+10/7×(-9)
=-2/7-90/7
=-92/7
=-13又7分之1