Solution:

Happy Birthday To You

Explanation:
Happy + Bird(-d) + sunday(-sun) + to(2) + you(u)

Solution:

3 + 3 = 8 can be set true by moved to one of two solution.
A) 5 + 3 = 8
B) 3 + 5 = 8

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.

Solution:

Three possible ways are shown in the image below.

Solution:

It can be solved as below.

Solution:

It can be solve as shown below.

Solution:

Can be done smartly as shown below.