The Taxpayer Assistance Center provides taxpayer assistance to help in the preparation of individual tax returns. The amount of assistance (A) that can be provided is a function of the number of professional accountants (P) and trained tax preparers (T) that are employed. The function given by: A = 500P+200T+50PT. TAC has budgeted $700,000 for a new office to pay accountants and the tax preparers. It pays an accountant $100,000 and a tax preparer $50,000. Calculate the marginal cost of providing additional assistance.