13/20=26/40
7/8=35/4016分之9,40分之11通分9/16=45/8011/40=22/8012分之5,36分之11,48分之13通分5/12=60/14411/36=44/14413/48=39/14411分之5,20分之7,5分之3通分5/11=100/2207/20=77/2203/5=132/220