Solve each of the following problems using the formulas for compound interest, the effective rate of interest, and the present and future values of annuities. Show your work, in particular how you start the problem: which equations you are using and where you are putting the variables.

The Sanderson family is planning on refinancing their home. 10 years ago, they borrowed $160,000 to finance the purchase of their home, taking out a 30-year mortgage at 5% interest compounded monthly. Now interest rates have dropped to 4.2%, and they plan on taking out a 20-year mortgage at 4.2% interest compounded monthly. What is their current monthly payment? What would be their new monthly mortgage payment? How much money should they expect to save each month on their monthly mortgage payments? Over the course of the loan, what will their overall savings be, compared to keeping the old mortgage?