5/18
请采纳谢谢
5/6-2/3+1/9=5/6-(2/3-1/9)=5/6-(6/9-1/9)=5/6-5/9=5×(1/6-1/9)=5×(3/18-2/18)=5/18
简便计算5/6-2/3+1/9=5/6-4/6+1/9=1/6+1/9=5/18
5/6-2/3+1/9=5/6-6/9+1/9=5/6-5/9=15/18-10/18=5/18
5/6-2/3+1/9=5/6-4/6+1/9=1/6+1/9=3/18+2/18=5/18