4/5-2/9+4/5+2/9=26/45+4/5+2/9=62/45+2/9=72/45=1又3/5呵呵有问题找我啊
4/5-2/9+4/5+2/9=(4/5+4/5)-(2/9-2/9)=8/5-0=1又3/5
4/5-2/9+4/5+2/9=4/5+4/5=1又3/5
4/5-2/9+4/5+2/9=4/5+4/5=8/5
4/5-2/9+4/5+2/9=(4/5+4/5)+(2/9-2/9)=8/5+0=8/5