6/15*5/7+8/15/7/5=

问题描述:

6/15*5/7+8/15/7/5=

6/15*5/7+8/15/7/5
=6/15*5/7+8/15*5/7
=5/7*(6/15+8/15)
=5/7*14/15
=2/3