Creating a scoring sheet for race series

I was going to ask this in the "formulas" section, but I think describing the result I'd like to achieve will get me a better answer than asking "how do I" do what I think is the correct way...

I am trying to track points standings for a 10-round race series. Each weekend, we run two heats for each class, with first place being awarded 25 points, second being awarded 20, and so on.

So for example, if "Jeff" gets first place in both heats on the first two race weekends (4 races total), his finishes would be listed as "1" (or I could live with having to enter "1st" or even "first"), but when I total his points at the bottom of the column, I need for those 4 heat wins to total 100 points (25 for each win).

What is the best way to accomplish this? If I could simply make 1=25, 2=20, 3=16, 4=13, 5=11, and so on down to 15th place, that would really be the simplest thing to do, so long as it doesn't screw up my simple "sum" function for the columns.