Solution:

XI - I = X

Explanation:
Remove I (Roman equivalent of number 1) from the left side, you will the get the number on the right.
29 - 1 = 30
XXIX - I = XXX (Roman equivalent of number 30)

14 - 1 = 15
XIV - I = XV (Roman equivalent of number 15)

9 - 1 =10
IX - I = X (Roman equivalent of number 10)

Similarly,
11 - 1 = 10
XI - I = X (Roman equivalent of number 10)

Solution:

21982030

Explanation:
Next number formed is (number * (number-2)) - number;
i.e
(5 * 3) - 5 => 10
(10 * 8) - 10 => 70
(70 * 68) - 70 => 4690
(4690 * 4688) - 4690 => 21982030

Solution:

5 of clubs.

Explanation:
The 5th number is equal to the sum of first four number (recursively until its value <=13). The suit will be same as of biggest card.
eg Row1:
5 + 7 + 3 + 11 = 26 = 8
Since Maximum value is Jack of hearts, therefore, we will get 8 of hearts

Similarly for the last row
12+13+2+5 = 32 = 5
Since Maximum value is King of a club, therefore, we will get 5 of a club.

Solution:

Z

Explanation:
The numeric value of the first two alphabets adds up to the numeric value of the last alphabet.

Solution:

TH

Explanation:
1st 2nd 3rd 4th 5th

Solution:

121

Explanation
Tables consist of squares of the number from 4 to 12.
11^2 = 121.

Solution:

3

Explanation:
Digits are represented in binary form where a ball is 1 and a ring is 0.
001 = 1
010 = 2
100 = 4
011 = 3

Solution:

2003.

Explanation:
Its a series of prime numbes.

Solution:

O

Explanation :
6 + 6 + 6 = N (last letter of sum i.e. eighteen)
7 + 7 + 7 = E (last letter of sum i.e twentyone)
8 + 8 + 8 = R(last letter of sum i.e twentyfour)
Therfore
0 + 0 + 0 = O (last letter of sum i.e. zero)

Solution:

28745

Explanation

New Number = (Last Number +1 ) * 9
and Then New Number = (Last Number - 1 ) * 8 and so on.

i.e
1
(1+1) * 9 = 18
(18-1) * 8 = 136
(136+1) * 7 = 959
(959-1) * 6 = 5748
(5748+1) * 5 = 28745
(28745-1) * 4 = 114976
(114976+1) * 3 = 344931