a. Calculate the quantity sold in two months of a store with two outlets (Unit: 1.000 products)
\begin{tabular}{|c|c|c|c|c|}
\hline Month 1 & A & B & C & D \\
\hline Outlet 1 & 10 & 2 & 40 & 15 \\
\hline Outlet 2 & 4 & 1 & 35 & 20 \\
\hline
\end{tabular}
\begin{tabular}{|c|c|c|c|c|}
\hline Month 2 & A & B & C & D \\
\hline Outlet 1 & 12 & 4 & 20 & 10 \\
\hline Outlet 2 & 10 & 3 & 15 & 15 \\
\hline
\end{tabular}
b. Calculate the revenue gained in two months of the store, given the prices of \( A, B, C \) and \( D \) correspondingly being 10, 20, 30 and 40 thousands in VND.