(Present value) What is the present value of the following future amounts?

a. $600 to be received 10 years from now discounted back to the present at 10 percent.

b. $400 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 4 percent.

d. $1,100 to be received 4 years from now discounted back to the present at 20 percent.