Hey there!
The sample of NF₃ contains 8.02 moles fluorine atoms.
There are 3 fluorine atoms in each molecule, so there will be 1/3 of the moles of fluorine.
8.02 / 3 = 2.67
There are 2.67 moles of NF₃ in a sample that contains 8.02 moles fluorine atoms.
Hope this helps!
