A magazine publisher has a fixed amount of monthly production costs. If each month he sells 400 copies of the magazine, his monthly profit is $\$4600$ and if he sells $300$ copies, his monthly profit is $\$2500$. What are the publisher's monthly production costs ?

Question

$\begin{array}{1 1}\text{(a) \$3800} \\ \text{(b) \$3500} \\ \text{(c) \$3000} \\ \text{(d) \$3200}\end{array}$