1-1/14+8/21+9/14-17/35-3-6/7
=1-3+(9/14-1/14)+8/21-17/35-6/7
=-2+4/7-6/7+8/21-17/35
=-2-2/7+8/21-17/35
=-2-6/21+8/21-17/35
=-2+2/21-17/35
=-2+10/105-51/105
=-2-41/105
=-2又105分之41
1-1/14+8/21+9/14-17/35-3-6/7
=1-3+(9/14-1/14)+8/21-17/35-6/7
=-2+4/7-6/7+8/21-17/35
=-2-2/7+8/21-17/35
=-2-6/21+8/21-17/35
=-2+2/21-17/35
=-2+10/105-51/105
=-2-41/105
=-2又105分之41