X-(3/14+4/7)=1/2X=1/2+(3/14+8/14)=1/2+11/14=7/14+11/14=18/14=1又2/7检验:1又2/7-(3/14+4/7) =18/14-(3/14+8/14) =18/14-11/14 =7/14=1/2正确
X-(3/14+4/7)=1/2
X-11/14=7/14
X=9/7