There are two types of annuities as follows:

a. An n-year annuity that pays out X at the end of each quarter. The present value of this annuity at interest rate i is 1,236.69.
b. An n-year annuity that pays out X at the end of each semester. The present value of this annuity at interest rate i is 607.71.

Using the same interest rate i, determine the present value of an n-year annuity that pays X at the end of each year.

please answer it manually not with excel. thank you.