\(\frac{1998.1996+1997.11+1985}{1997.1996-1995.1996}\)
\(=\frac{1998.1996+11.\left(1996+1\right)+1985}{1996.\left(1997-1995\right)}\)
\(=\frac{1998.1996+11.1996+11+1985}{1996.2}\)
\(=\frac{1998.1996+11.1996+1996}{1996.2}\)
\(=\frac{1996.\left(1998+11+1\right)}{1996.2}\)
\(=\frac{2010}{2}=1005\)