Thread: Need formula to reduce calculation by specific number

Hi -
I am trying to figure out a final budget amount for HOA fees but need it to reduce by a specific amount...i.e. We owe HOA dues of $120 per lot per quarter for 85 lots but budget to sell 3 lots per quarter so each quarter's calculation will need to reduce by 3 from the previous quarter. I need to figure what my total spend is until we get to zero lots. I can't figure out any way to calculate it other than manually - I thought I could do an amortization schedule or even a present value formula with 0% interest but I can't figure out how to get it to work. I am completely stuck!

Have you tried using GoalSeek?