\input{umtest-preamble}
\usepackage[slash-delimiter=frac]{unicode-math}
\setmathfont{Cambria Math}
\begin{document}
\[ \left.\left[\begin{array}{cc} 
     a & b \\ c & d
   \end{array}\right]
   \middle/
   \left[\begin{array}{cc}
     1 & 1 \\ 1 & 0
   \end{array}\right]\right.
\]
\end{document}