Case $1$: Refinance outstanding loan amount:

Assume that you have a thirty$-$year mortgage for $$200,000$ that carries an interest rate of $9\mathrm{.}00\%.$ The mortgage was taken three years ago. Since then, assume that interest rates have come down to $7\mathrm{.}50\%,$ and that you are thinking of refinancing the existing mortgage with another thirty$-$year mortgage. The cost of refinancing is $2\mathrm{.}50\%$ of the loan. Assume also that you can invest your funds at $6\%.$ Is it beneficial to refinance?

Case $2$: Refinance outstanding loan amount:

Redo the above example assuming that you refinance the original loan amount instead of outstanding loan amount.