Official solution
\[x = {e^{y + {e^{y + .....\infty }}}}\,\, \Rightarrow x = {e^{y + x}}.\]
Taking log.
\[\log \,\,x = y + x\]
\[ \Rightarrow {1 \over x} = {{dy} \over {dx}} + 1\]
\[ \Rightarrow {{dy} \over {dx}} = {1 \over x} - 1 = {{1 - x} \over x}\]