How much would $100 invested at 6% interest compounded mothly be worth after 20 years? round answer to the nearest cent

Alright, so in order to solve this problem, you need to know the formula for compound interest, which is 
A= P(1+r/n)^nt
A is the final amount, P is the beginning amount, r is the rate it is being compounded at, n is the number of compounds per year, and t is obviously the time or number of years

Since it is compounded monthly, n will equal 12, as there are 12 months in a year.

Plug in what you have and you get A= 100 (1 + .06/12)^(12)(20)
A=331.02

It should be a or d i’m not sure