110. Let x=lga,y=lgb,z=lgc, since a,b,c are real numbers greater than 1, so x,y,z> 0.
logabc+logbca+logcab⩾4(logabc+logbca+logcab)⇔yx+zx+zy+xy+xz+yz⩾y+z4x+z+x4y+x+y4z
It is only necessary to prove xz+yz⩾x+y4z, etc., which is equivalent to proving x1+y1⩾x+y4. This is obvious.