54*56/55-27*28/27 马上要
问题描述：
54*56/55-27*28/27 马上要
答
54*56/55-27*28/27
=（55-1）*56/55-28
=55*56/55-56/55-28
=56-28-1-1/55
=27-1/55
=26又55分之54