APR with Monthly Compounding

Suppose that the interest rate is $5\%$ APR with monthly compounding.

$($a$)$ What is the present value of $$100$ that will be paid three years from now?

$($b$)$ What is the present value of a perpetuity that will pay $$10$ every month and forever, starting a month

from now?

$($c$)$ What is the present value of an annuity that will pay $$10$ every month for three years, starting a month

from now?