please help me to answer these questions as soon as posiple

2)An investor just purchased an office building for $400,000. He knows for certain that he can sell the building for $450,000 in 3 years. About how much does he need to charge in annual rent in order to achieve a 12% annual return on the deal? (round to nearest whole number)

4) You need to accumulate $75,000 in 12 years. How much should you put in your 10% account at the end of each year to accumulate the necessary funds?

10) An investor spent $30,000 on a vacant lot 6 years ago that he just sold for $100,000. What is the investor's annual rate of return?

9) Assume a property is priced at $5,000 and has the following income stream:

Yr 1:$1,000; Yr 2: -$2,000; Yr 3: $3,000; Yr 4: $3,000

Would an investor with a required rate of return of 15% be wise to invest a the current price?