1-14/9+21/8+7/1-35/17-3又7/6
倒了
1-9/14+8/21+1/7-17/35-27/7
=5/14+8/21-17/35-26/7
=31/42-17/35-26/7
=31/42-(17/35+26/7)
=31/42-147/35
=-727/210