Suppose in a certain community, there will be M(r) thousand refinanced mortgages when the 30-year fixed mortgage rate is r%, where M(r) 1 + 0.05r for 1 r≤8 1 + 0.004,² a. For what values of r is M(r) increasing? b. For what interest rate r is the number of refinanced mortgages maximized? What is this maximum number?

Please solve A & B. 

REFINANCING When interest rates are low, many homeowners take the opportunity to refinance their mortgages. As rates start to rise, there is often a flurry of activity as latecomers rush in to refinance while they still can do so profitably. Eventually, however, rates reach a level where refinancing begins to wane.

Suppose in a certain community, there will be

M(r) thousand refinanced mortgages when the

30-year fixed mortgage rate is r%, where

Can you please solve this ASAP. Please show me the steps I have no idea how. I am doing a practice problem.