(Present value) What is the present value of the following future amounts? a. $900 to be received 10 years from now discounted back to the present at 9 percent b. $300 to be received 6 years from now discounted back to the present at 8 percent c. $1,050 to be received 13 years from now discounted back to the present at 3 percent d. $1,100 to be received 5 years from now discounted back to the present at 20 percent