What does this below rebus puzzle mean?

Given below is simple addition with a defined pattern pattern:
7 + 7 = 2
8 + 8 = 4
8 + 5 = 1
6 + 9 = 3
10 + 11 = 9

Can you analyze the pattern and find out the answer for:

4 + 9 = ?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

What Time Should the last watch show in the below figure?

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

What work can one never finish?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

In the image given, you can find several triangles. Can you count them all?

If eleven plus two equals one, what does nine plus five equal?