-99又1/3-｛-72又5/6-（25.75-3又1/2｝

-99又1/3-｛-72又5/6-（25.75-3又1/2｝
=-(99+1/3)-{-(72+5/6)-[25.75-(3+1/2)]}
=-99-1/3+(72+5/6)+(25.75-3-0.5)
=-99-1/3+72+5/6+22.25
=(-99+72)+(5/6-1/3)+22.25
=-27+0.5+22.25
=-4.25