Whats the discount rate that would make you indifferent between these two options: $5,000 in year 2 vs. $20,000 in year 30? (Answer without percentage sign and round to 2 decimal places)

Please help me with this equation, I cannot figure it out for the life of me! I have asked 10 of my friends and none of them can get it. I am just trying to understand the problem and how in the world to figure out the answer