Let $$A = \left[\begin{array}{rr} -6 & 1 \\ -6 & 5 \\ \end{array}\right] \quad\hbox{and}\quad B = \left[\begin{array}{rr} 9 & 0 \\ -5 & 4 \\ \end{array}\right].$$ Then $$AB - BA = \left[ \begin{array}{rr} c_{11} & c_{12} \\ c_{21} & c_{22} \\ \end{array}\right]$$ where
$c_{11}$ = ,
$c_{12}$ = ,
$c_{21}$ = ,
$c_{22}$ = ,