你好!5/9-(7/8-4/9)=5/9-(63/72-32/72)=5/9-31/72=40/72-31/72=9/72=1/8希望可以帮到你请采纳谢谢!
5/9-(7/8-4/9)=5/9-7/8+4/9=5/9+4/9-7/8=1-7/8=1/8
5/9-(7/8-4/9)=5/9-7/8+4/9=1/8
5/9-(7/8-4/9)=5/9+4/9-7/8 =1-7/8 =1/7