please answer all 3 questions

3. If your bank promises to double your money in 15 years, what interest rate are they offering? Charlie has just bought a house with a 20 -year, 6%,$70,000 mortgage on which he is paying $629.81 per month. If Charlie sells the house after 12 years, how much must he pay the bank to completely pay off the mortgage at the time of the 144th payment? 6. How much money should I invest today to create a trust fund for my successors if I want them to receive $20000 a year and the interest rate offered is 5% ? [Hint: Trust funds are perpetual]