\(\require{cancel}\newcommand{\cancelhighlight}[1]{\color{blue}{{\cancel{#1}}}}
\newcommand{\secondcancelhighlight}[1]{\color{green}{{\bcancel{#1}}}}
\newcommand{\thirdcancelhighlight}[1]{\color{orange}{{\xcancel{#1}}}}
\newcommand{\lt}{<}
\newcommand{\gt}{>}
\newcommand{\amp}{&}
\definecolor{fillinmathshade}{gray}{0.9}
\newcommand{\fillinmath}[1]{\mathchoice{\colorbox{fillinmathshade}{$\displaystyle \phantom{\,#1\,}$}}{\colorbox{fillinmathshade}{$\textstyle \phantom{\,#1\,}$}}{\colorbox{fillinmathshade}{$\scriptstyle \phantom{\,#1\,}$}}{\colorbox{fillinmathshade}{$\scriptscriptstyle\phantom{\,#1\,}$}}}
\)