What is the present value of the following future amounts?

a) $800 to be received 10 years from now discounted to the present at 10%

b) $300 to be received 5 years from now discounted to the present at 5%

c) $1000 to be received 8 years from now discounted to the present at 3%

d) $1000 to be received 8 years from now discounted to the present at 20%