(Present value) What is the present value of the following future amounts? a. $800 to be received 8 years from now discounted back to the present at 10 percent b. $300 to be received 7 years from now discounted back to the present at 9 percent c. $1,100 to be received 12 years from now discounted back to the present at 5 percent d. $1,250 to be received 6 years from now discounted back to the present at 18 percent