Get a number X less than anther number

Hello & thanks for looking at least this far.


<<<--- Pic 2
In pic 2 ^^^ you can see a list of numbers in column "AF", these numbers are ten lower than the numbers in pic 1 (Column "N"). So in pic 1, the number on the top row is 6.4 and on the top row of pic 2 the number is 5.2 - 10 lower than 6.4 on my database list in pic 3. If you look at pic 3, you'll see that 6.4 is at the top in column A row 160. Ten lower than this is column A row 170, which shows 5.2.

<<<--- Pic 1


<<<--- Pic 3


So, what I want to do is find a formula to pull the number from (pic 3) ^^^ Column A row, that is X lower, in this case 10 lower, than the numbers in pic 1. To clarify, I type the number 6.4 in column "N", I want the number ten lower than 6.4 from column A in pic3 to automatically go in the corresponding row in colmn "AF" (pic 2).

I hope that's clear enough & thanks once again for looking at least this far.