Advice from most financial advisers states to spend no more than 28% of one's gross monthly income for one's mortgage payment and to spend no more than 36% of one's gross monthly income for one's total monthly debt. Suppose a family has a gross annual income of $42,000.

a. What is the maximum amount the family should spend each month on a mortgage payment?

b. What is the maximum amount the family should spend each month for total credit obligations?

c. If the family's monthly mortgage payment is 80% of the maximum they can afford, what is the maximum amount they should spend each month for all other debt?