Please answer the following and show all work.

An investment promises to pay $20,000 in 10 years if you invest $10,000 today. What is the implied rate of interest? An investment pays $5,000 per year for the next 10 years. If your discount rate is 7%, how much are you willing to pay for this investment today? You want to purchase a new car, and you are willing to pay $30,000. If you can invest at 5% per year and you currently have $15,000, how long will it be before you have enough money to pay cash for the car