Super easy. All you do is replace the numbers in your table with the corresponding letter. In this case we have a table of s and f.
Example for row two: f = s + 12. Replace s with 4 ( 4 is from your s column so you would replace it with that) then solve and plug in your answer (When you solve your answer, it will go under f column).16 = 4 + 12 . f = 16, s = 4.
