Answer: removing 1 x-tile from each side
Step-by-step explanation:
Xy = 12 because if you look at the pattern the top one is 16 and the bottom one is 8 so the middle of those would be 12.
81,149, 274.... adding three numbers from the last would help you
like if you take 7 = 4 + 2 +1
or 13 = 7 + 4 +2
similarly 44+24+13 = 81
81+44 +24 = 149
149 + 81 +44 = 274
hope you get it!