In this one according to my instructor
note when wind constant pet = pnr
from the question i deduced in this question few words are missing related 500kg fuel
but let assume without reserve and 500 kg fuel
5000kg fuel = 1200nm
so 500kg fuel = x
cross multiply 5000/500 = 1200/x
x = 1200/10 = 120nm
final result 1200 + 120 = 1320 nm answer