please solve this questions

Exercise 4. [4] The present value at interest rate i of a 20-year annuity-immediate with level annual payment is X. At the same interest rate, the present value of a 40-year annuity-immediate with the same annual payment amount is 1.5 X. Calculate i. Exercise 5. [4] To accumulate 6000 at the end of 5n years, deposits of 80 are made at the end of each of the first n years and 160 at the end of each of the next 4n years. The annual effective rate of interest is i. you given (1 + i)" = 3.0. Calculate i. Exercise 6. [4] At an annual effective interest rate of i, i > 0%, the present value of a perpetuity paying 10 at the end of each 2-year period, with the first payment at the end of year 2, is 42. At the same annual effective rate of i, the present value of a perpetuity paying 1 at the end of each 3-month period, with first payment at the end of 3 months, is X. Calculate X