14分之5×6分之5-12分之7×14分之5+20分之9×14分之5
问题描述：
14分之5×6分之5-12分之7×14分之5+20分之9×14分之5
简便计算
答
5/14*5/6-7/12*5/14+9/20*5/14
=5/14*(5/6-7/12+9/20)
=5/14*(1/2+1/3-1/3-1/4+1/4+1/5)
=5/14*(1/2+1/5)
=5/14*7/10
=1/4