Solution:

It is possible when you write the numbers in their Roman form.
XI (11) - When you remove me from XI, it becomes X i.e. 10
IX (9) - When you remove me from IX, it becomes X i.e. 10

Solution:

There are various answer possible

Solution 1 :
Pull the snake and throw towards the lion. The lion will fear for the fraction of the time. Use this time to jump towards the axe. Kill the lion using an axe and feed the dead body of the lion to the crocodile.

Solution 2:
This scenario can only be possible in the dream. so boy should wake up and escape.

Solution 3:
Pray to god.

Solution:

987 is sam house number.
Pricing is simple 10$ for each number.

Solution:

Your friend's statement is actually true and it's not different from what you have answered.

25 - 55 + (85 + 65) = 25 - 55 + 150 = 120 = 5!
5! (factorial) = 5 * 4 * 3 * 2 * 1 = 120

Yes, that was a tricky question, quite capable to confuse anybody.

Solution:

1262

Sequence is based on formula:
Next = (1st Number)^2 - (2nd number)

7 12 37 ? 9142

7^2 - 12 = 37
12^2 - 37 = 107
37^2 - 107 = 1262 (Answer)
102^2 - 1262 = 9142

Solution:

The numbers that have been written over the calendar are:
12, 4, 8 and 3

A few numbers have been circled under particular months. The curious thing is that the numbers that have been written are the same number of corresponding months under which the dates have been marked.

What we can judge by the overall calendar is that the dates that have been marked may refer to the letters at that position in the month's name. In addition, the written numbers can be the position of those letters. Let's simplify below:

12th month is December
The number marked under December = 5
The fifth letter of December = M

4th month is April
The number marked under April = 4
The fourth letter of April = I

8th month is August
The number marked under August is 6
The sixth letter of August = T

3rd month is March
The numbers marked under March are 4 and 5
The fourth and fifth letter of March = C and H

When you combine the letters, you get the name as MITCH.
Therefore, Mitch is the killer.

Solution:

Can be found on the pic below.

Solution:

It can be done as shown in the picture below.

Solution:

We are deck Of Cards

Solution:

It can be done in image below.