What is the principal invested at 4.75% compounded semi-annually from which monthly withdrawals of $240 can be

Question:

What is the principal invested at 4.75% compounded semi-annually from which monthly withdrawals of $240 can be made
(a) At the end of each month for 25 years?
(b) At the beginning of each month for 15 years?
(c) At the end of each month for 20 years but deferred for 10 years?
(d) At the beginning of each month for 15 years but deferred for 12 years?
(e) At the end of each month in perpetuity?
(f) At the beginning of each month in perpetuity?