please help :)

art 2: Time Value of Money (warm up) 1. What amount received at the end of 20 years is equivalent to $100 today, given an opportunity cost of 14% ? 2. What amount received at the end of 15 years is equivalent to $100 received at the end of each year for 15 years, given an opportunity cost of 12% ? 3. What present amount is equivalent to $100 received at the end of each year for 8 years, given an opportunity cost of 6% ? 4. What present amount is equivalent to $100 received at the end of each year for 8 years, given an opportunity cost of 12%