In a LaTeX document I have about 70 images which are scaled using the graphicx-package and
\includegraphics[scale=0.8]{foo.pdf}
where the scaling factor varies. Now I would like to rescale them all with a common factor, like
\newcommand*{\factor}{0.75}
\includegraphics[scale=\factor * 0.8]{foo.pdf}
except that is no LaTeX syntax. Can anyone provide a smart solution?