Solution:

60

Explanation:
1 + 5 = 12
But it can be true only if we multiply both digits with 2 and then add:
1*2 + 5*2 = 12

2 + 10 = 24
But it can be true only if we multiply both digits with 2 and then add:
2*2 + 10*2 = 24

3 + 15 = 36
But it can be true only if we multiply both digits with 2 and then add:
3*2 + 15*2 = 36

Similarly,
5 + 25 can be true only if we multiply both digits with 2 and then add:
=> 5*2 + 25*2 = 60

Therefore, the missing number is 60.

Solution:

If we place a decimal between the numbers it will become 5.9 which is what we needed.

Solution:

5832/17496
This fraction will give the desired result i.e. 1/3.

Solution:

3^2 = 4 + 5
(^ is used for squaring the term, it is not used here as a mathematical symbol.)

Solution:

We know that there may be many possibilities and if you find one it is great. For reference we have given one solution below.

(1 + (3 + 4*5)*6)*2

Solution:

88 + 88/88

Solution:

4 x (182) = 728

Solution:

117(1+3+5,3+4)

Solution:

444 + 444 + 44 + 44 + 4 + 4 + 4 + 4 + 4 + 4 = 1000

Solution:

54
x3
===
162