This is a problem set from my individual work in the course of Economic.
A businessman plans to earn 10 000 UAH in 2018, and additionally 50 000 UAH in 2020. His discounted income equals to 40 000 UAH.
Find the interest rate (r). Explain your calculations.
I have no idea what to do. As I understood all my income which I will get in the future (50 000 + 10 000) is equal to 40 000 at the moment. So $60 000 = 40 000$ and so $r=0.66$ but it`s too straight and I have no idea how to solve it another way.