Check pairs (top cell, bottom cell): 

S → 19 and 20 → +1 8 → J (10) → +2 W (23) → 25 → +2 16 → T (20) → +4 A (1) → 4 → +3 5 → K (11) → +6 C (3) → 7 → +4 X (?) → L (12) → difference is 12 - ? A (1) → Y (?) 4 → N (14) We look for a consistent pattern. Right-side pattern seems to be increasing by fixed differences. The only option fitting the pair (X → L), meaning X must be 4 (since 12 - 4 = 8, matching nearby jumps), and Y must be 6 (since A=1 to Y=6 makes sense in pattern).