[(1/2+2/3)除5/6-1/3]除1/7-1/3
=(7/6÷5/6-1/3)÷1/7-1/3
=(7/5-1/3)÷1/7-1/3
=49/5-7/3-1/3
=49/5-8/3
=9+4/5-2-2/3
=7又2/15