Please help me with this question ASAP

Mr. Harrison is choosing a house to buy. His gross monthly income from the main job is $8,000. He also has a side business which yields another $1,000/ month for him. He is a "conservative" guy, so he does not own any credit card or any debt account. He is planning to use a 15% down payment on a 25 -year, 7.3% interest mortgage. Monthly property taxes and insurance are estimated at $120. (a) What is the most expensive house he can afford? (15 pts) (b) Mr. Harrison only has $60,000 in cash. Is it enough to cover his down payment? (5 pts) (c) What are his MDR and TDR? (10 pts)