Solution:

'T'

Explanation:
The letters around the center are actually depending on the letter in the center. They are advancing according to the numerical value of that letter.

For example, F, G, H and I are advancing by 1 because the center letter is A, which has the numerical value 1.

Again, G, K, S, and O are advancing by 4, because the center letter is D, which has a numerical value of 4.

Similarly, N has advanced by 6 from H, because the center letter is F, which has a numerical value of 6. Hence, the missing letter should be T.

Solution:

As you see in the image, we had to move just the circle number 1, 7 and 10 and it is done.

Solution:

73 & 48

Explanation:
We can get the number on the left by adding numbers above it and subtract the sum by 5. i.e.
8 + 11 - 5 = 14
14 + 10 - 5 = 19
19 + 16 - 5 = 30
30 + 21 - 5 = 46
46 + 32 - 5 = 73

Right column = left number above it + 2 => 46 + 2 => 48

Solution:

26

Explanation:
14 = 1^2 + 2^2 + 3^2
21 = 4^2 + 1^2 + 2^2
29 = 4^2 + 3^2 + 2^2
26 = 3^2 + 4^2 + 1^2

Solution:

July

Explanation:
Step 1 : Cut the image horizontally in 2 pieces
Step 2: Look into the bottom image. It will be read as July as shown in the image.

Solution:

A cigar stuck in the wall

Solution:

Horse = 10
Cowboy-Boot = 1
HorseShoe= 2
The Last equation = 21

Detailed Explanation :
Equation1:
3Horse = 30
=> Horse = 10 .....(1)

Equation2:
1Horse + 2HorseShoe + 2HorseShoe = 18
10 + 4HorseShoe =18
HorseShoe = 2 .....(3)

Equation3:
2HorseShoe - 2Cowboy-Boot = 2
4 - 2Cowboy-Boot = 2
=> Cowboy-Boot = 1 ... (2)

Equation4:
Cowboy-Boot+Horse*HorseShoe = 1+10*2
=>21

Solution:

The solution is provided in the image below.

Solution:

It's in the beer mug

Solution:

It's shown in the red circle below.