the most you can pay for an investment that pays you an X amount during one year = X$ / (1 + discount rate)
the most you can pay for an investment that pays you X amount during five years = [X$ / (1 + discount rate)] + [X$ / (1 + discount rate)²] + [X$ / (1 + discount rate)³] + [X$ / (1 + discount rate)⁴] + [X$ / (1 + discount rate)⁵]
