Solution:

20 more bullets

Explanation:
Initially, Willian has 'W' bullets and Pedro has 'P' bullets.

Based on statements, we have 2 equations
3P = W
2(P+10) = W-10

=> 2P + 20 = 3P - 10
=> 30 = P

P = 30 and W = 90.

Willian gave 10 bullets, therefore, need to give 20 more bullets so that they can 60 bullets each.

Solution:

Can be found on the pic below.

Solution:

16

Explanation:
9 [1x1] squares
5 [2x2] squares
1 [4x4] square
1 [4x4] square

9 + 5 + 1 + 1 = 16 squares.

Solution:

Either your read from start or from ends, it will be same

Solution:

2 degree below zero

Solution:

Since every bacterium divides into two in two minutes and we know the fact that the dish was half filled with bacteria at 3 pm, after exactly 2 minutes, all will divide into two and will fill the petri dish. Thus, the petri dish will become full at 3:02 pm.

Solution:

2 minutes (duration between 9:59 and 10:01)

Solution:

The last marble will be yellow.

Since marbles can only be taken out in pairs and you started off with an odd number of yellows there is always going to be one yellow left over that you'll keep putting back in the box until it's left on it's own.

Solution:

Everyone will done one day or other.

Abraham Lincoln era is too old and we expect most of them(if not all) to be dead by now.

Solution:

Here is a way to do it. We dont know if it can be done using some other arrangement or not. If you know, do send us.

4 | 3 | 8
9 | 5 | 1
2 | 7 | 6

Solution:

It can be solved as below.