Greetings!
To find the empirical formula you need the relative atomic mass of each element!
C = 12
F = 19
You can simply change the percentages into full grams
C = 13.64g
F = 86.35g
Then you use this to find the Number of moles = amount in grams / atomic mass
C = 13.64 ÷ 12 = 1.13
F = 86.35 ÷ 19 = 4.544
Then divide each number of moles by the smallest value:
C = 1.13 ÷ 1.13 = 1
F = 4.544 ÷ 1.13 = 4.02 ≈ 4
So that means that there are 1 Carbon and 4 Fluorine. This means the empirical formula would be:
CF₄
Hope this helps!