please help me solve this!!!! I really just need a clear explanantion because the Question help doesnt explain anything

Problem 5-52 (similar to) Overview, question 1? cf 20, 9 complete 55 Question Help : [Pemehries) What is the present value of the following? a. A $300 perpetuity discounted beck to the present at 9 percent b. A $6,000 perpetuity discounted back to the present at 13 percent 4:. A $180 perpetuity discounted beck to the present at 10 percent d. A $85 perpetuity discounted back to the present at 6 percent a. What is the present value of a $300 perpetuity discounted back to the present at 9 percent? 5 (Round to the nearest cent.)