In a 9 letter word SANKRANTI, there are 3 vowels i.e. two A's and one I.
Any group of letters can be arranged in n!/(P1!*P2!*..) ways, where n=Total letters and P1, P2 are number of repetitions.
We have to arrange SNKRNT (AAI) considering it a 7 letters word, where N repeats twice.
Now, these 7 letters can be arranged in 7!/2! ways with 2 repetition of N.
Vowels AAI can be arranged among themselves in 3!/2! ways with 2 repetition of A.
Hence, total number of arrangements = (7!/2!)*(3!/2!) = 7560