Suppose a firm has the following production technology: one work is required to operate on one machine (capital). More than one worker on the same machine will have a zero MPL. One worker operating on two or more machines will also have a zero MPK. If wage is $100 and rental rate for capital is $500, what is the lowest cost of labor and capital usage for this firm to produce 300 output? (Hint: this is the case when labor and capital are perfectly complements)