Q1) The present price of a firm's stock should reflect the discounted value of the expected future cash flows to shareholders (dividends). Suppose that you are expecting a future cash flow of 50000 dollars after 5 years from now, how much this 50000 dollars worth today if discount rate is 4%?

Q2) Consider a stimulus program that intends to spend $300 billion every year, for three years. Assuming a 3% discount rate, what is the present value of the program?

Q3) Assume that you're in charge of the nation's economics. Suppose that projected 2023 deficit is $418 billion and projected 2030 deficit is $1,345 billion. In present value terms, how large is the difference of the two budget shortfalls? Assume a 3% discount rate.

I need to explanation as math perspective please. specifically for Q1.