答案1
加载calc
包,
\documentclass[12pt, twodisem]{book}
\usepackage{calc}
\usepackage{graphicx}
\begin{document}
\includegraphics[width=\linewidth-1.0cm]{example-image}
\end{document}
或者包裹\linewidth-1cm
里面\dimexpr ... \relax
\documentclass[12pt, twodisem]{book}
\usepackage{graphicx}
\begin{document}
\includegraphics[width=\dimexpr\linewidth-1.0cm\relax]{example-image}
\end{document}