First number = 8 and the sum of the digits of the second number is 2 + 8 = 10.

Thus the difference of the first number and the sum of the digits of second number is 10 - 8 = 2.

Similarly, the sum of the digits of third number is 2 + 7 = 9.

Hence the sum of digits of fourth number should be 2 more than 9 i.e. 11

Hence, fourth number is 65.

As, 123 → 13²

As, 235 → 25³

The middle digit of first term becomes power to the next term.

14 = (2 x 9 - 4)

26 = (2 x 15 - 4)

? = 15