All the numbers are perfect cubes.
Let us see
As, 8 = 2³
1331 = 11³
4913 = 17³
Similarly, 64 = 4³

Each set is made of the digits 2, 4, 6, 8

In each set
2nd number = 1st number + 10-1
3rd number = 2nd number + 101
Let use see
As, 223 + 101 = 324
and 324 + 101 = 425
Similarly, 554 + 101 = 655
and 655 + 101 = 756

Set of consecutive odd prime numbers.

In (12, 20, 28), every next number is obtained by adding 8 with the previous number and similarly, in (18, 30, 42).
every next number is obtained by adding 12 with the previous number.

In each set
2nd number = 1st number x 7
and 3rd number = 1st number x 8
Let us see
As, 14 = 2 x 7
and 16 = 2 x 8
Similarly, 21 = 3 x 7
and 24 = 3 x 8

As, 841= (29) ²
Similarly, 289 = (17)²

As for finishing the 'Leather', 'Tanning' method is used, in the same way for 'Fireworks' pyrotechnics is used

As, F = 6 ? 6³=216
Similarly, L = 12 &rArr: (12) ³=1728
Therefore = 1728

As, sum of digits of 584 = 5 + 8 + 4 = 17
and sum of digits of 488 = 4 + 8 + 8 = 20
Similarly, sum of digits of 294 = 2 + 9 + 4 =15
? Sum of digits of 378 = 3 + 7 + 8 = 18
Here, difference of both are (20 - 17 ) = ( 18 - 15 ) = 3
Therefore ? = 378 is an answer.