1又2/9-(2/9-3/4)(过程)
=1又2/9-2/9+3/4
=1+3/4
=1又3/4
3/4*3/11-3/11*1/4+3/11*1/2(过程)
=3/11×(3/4-1/4+1/2)
=3/11×(1/2+1/2)
==3/11×1
==3/11
1又2/9-(2/9-3/4)(过程)
=1又2/9-2/9+3/4
=1+3/4
=1又3/4
3/4*3/11-3/11*1/4+3/11*1/2(过程)
=3/11×(3/4-1/4+1/2)
=3/11×(1/2+1/2)
==3/11×1
==3/11