Please do not use financial calculator. I want to know the formula.

Suppose that the annual percentage rate (compounded semi-annually) is 10%. Calculate the present value of the following perpetuities:

(a) a perpetuity that pays $500 every year with the first payment occurring in 2 years from now;

(b) a perpetuity that pays $500 every year with the first payment occurring in 3 years from now;

(c) a perpetuity that pays $500 evey six months with the first payment occurring in 4 years from now;

(d) a perpetuity payable annually with the first payment of $100 now and each additional payment growing at 2% annually.

Thank you! (Please show me the process in detail, Thank you again!)