D$)$ Using the real$-$life application below, determine the following:

Suppose a small manufacturing company produces a standard type of surfboard. If fixed costs are $$700$ per week, standard type of surfboard variable costs are $$70$ per board produced, and the high$-$performance competition surfboard variable costs are $$100$ per board, find $C(14,7)$ when $C(x,y)=70070x100y.$