Solve a matrix equation
The unknown matrix is \(Z\)
Rows are ordered as Site 1 then Site 2, and columns as Week 1 then Week 2. All entries are exact
\[Z + G = H\]
\[G = \begin{bmatrix} 3 & 7 \\ 7 & 1 \end{bmatrix}\]
\[H = \begin{bmatrix} 4 & 12 \\ 8 & 6 \end{bmatrix}\]