Exercise $6\_$ch$4\_$no$5($Interest$-$only loan, refinancing$)$: Five years ago, you took an interest$-$only loan. The loan carries a $1\%$ monthly interest rate, and the loan principle is $$150,000.$ The loan has two more years $(24$ monthly payments to be paid at the end of every month.$)$

a$.)$ What is the monthly payment on the loan?

b$.)$ A financial advisor approaches you and offers to refinance the loan for a consultancy fee of $$8000.$ The new loan has the same characteristics as the current loan but carries a $0\mathrm{.}75\%$ monthly rate. Should you refinance the loan?