Compare the two codes:
SKIP → 5269
SILK → 2576
Common letters
Both words have S, I, K in common.
Common digits
Digits common in both codes:
5269 and 2576 → common digits are 2, 5, 6
So, S, I, K correspond to 2, 5, 6 (in some order).
Remaining letter
In SKIP, extra letter = P, extra digit = 9 ⇒ P → 9
In SILK, extra letter = L, extra digit = 7 ⇒ L → 7
L is coded as 7