(log2 + lg5 - lg8)/lg50 - lg40
问题描述：
(log2 + lg5 - lg8)/lg50 - lg40
答
(lg2 + lg5 - lg8)/(lg50 - lg40)
=lg(2*5/8) / lg(50/40)
=lg(5/4) / lg(5/4)
=1