5/6*1/19+20/9*2/19+25/18*6/19
问题描述：
5/6*1/19+20/9*2/19+25/18*6/19
答
=5/19×1/6+5/19×8/9+5/19×5/3
=5/19×(1/6+8/9+5/3)
=5/19×49/18
=245/342