Bruce Corporation makes four products in a single facility. These products have the following unit product costs:

$\backslash$table$[[,,$Proo,uct,,$],[,$A$,$B$,-,C,$D$],[$Direct materials,$$13\mathrm{.}90,$$$9\mathrm{.}80,$$$,10\mathrm{.}60,$$$10\mathrm{.}20$