I need help with these 3 questions.

6. Eric deposits 12 into a fund at time 0 and an additional 12 into the same fund at time 10. The fund credits interest at an annual effective rate of i. Interest is payable annually and reinvested at an annual effective rate of 0.75i. At time 20, the accumulated amount of the reinvested interest payments is equal to 64. Calculate i, i >0. A) 8.8% B) 9.0% C) 9.2% D) 9.4% E) 9.6% 7. (EA1) A 20-year immediate annuity is payable monthly. Immediately after the 43rd payment has been made, the present value of the remaining annuity payments is calculated to be X. N is the number of the payment after which the present value of the remaining annuity payments is less than for the first time. You are given d(4) = .08. Find N. A) 67 B) 68 C) 171 D) 172 E) 173 8. X is deposited at the beginnings of years 1-14. No deposits are made during years 15-32. (X 100) is deposited at the beginning of years 33-42. The annual effective rate of interest is 7%. The accumulated value of the deposits at the end of 42 years is $100,000. Find X. A) Less than 555 B) At least 555 but less than 575 C) At least 575 but less than 595 D) At least 595 but less than 615 E) At least 615