Solution:

The brain teaser can be solved as shown in the image below.

Solution:

It can be done in 8 moves as shown in the animated image below.

Solution:

Nightmare.

Explanation:
(K)night + mare (A mare is the female of a horse)

Solution:

See the picture for the answer. Don't worry if you have a different answer; this question can be solved with different numbers. However, do post your answer in the comments.

Solution:

It can be done as shown below.

Solution:

It can be solved as shown.

Solution:

It can be done as shown below.

Solution:

5

Explanation
First three equation in the image can be written as :
a) 3 BED = 30
b) 2 BED + BUS = 40
c) BED + 2 BUS+ 2 TROPHY = 60

From equation a)
BED = 10

From equation b)
BUS = 40 -20 =20

From equation c)
10 + 40 + 2 TROPHY = 60

TROPHY = 5

Solution:

Eye

Explanation :
It is written with two letters. ( 'E' and 'y')
It is said with the one. ( I )
It usually is seen with the two. ( two eyes)

Solution:

Costa

Explanation:
c + 1 characters-> d
o + 2 characters-> q
s + 3 characters-> v
t + 4 characters-> x
a + 5 characters-> f

=> dqvxf = costa