Assume the interest rate is 5% per year and that you can borrow and lend any amount at that rate, with interest paid or received annually.

What is the present discounted value of a flow of receipts of 10,000 each year for 10 years, received in annual instalments and beginning 1 year from now?

the correct answer here is 77217.14, I ham not sure how to get this answer, it involves the use of sum of geometric progression, please explain well.