33

if you replace the spaces, the patern is clear and the solution is simple:

?
16-17  (16=6+10 ; 17=10+7)
6-10-7 (6=2+4;10=4+6;7=6+1)
2-4-6-1

16+17=33

Lisa

Statement 3 is always false, because when statement 1 is false statement 5 must be true and therefore statement 2 must also be true.
If statement 3 is false, statement 1 must be true.
If statement 1 is true then statement 5 is false.
Statement 4 is also false because statement 2 is false. If statement 4 was true then statement 2 would also be true.
So Christina is NOT a nurse.

20

They started with x and 3x balloons.
After giving 10 balloons they have x+10 and 3x-10 balloons and 2(x+10) = 3x-10.
This gives x=30
They started with 30 and 90 balloons.
After giving 10 balloons they have 40 and 80 balloons.
When John give Jacob another 20 balloons they both have 60 balloons

The black car was a hearse and the dead body lay in a coffin in the back.

The statements on last two envelopes are mutually exclusive, so one of them is true and the other one is false.
This means that the statement on the first envelope must be false and the money is in the first envelope.

The two stations are on a mountain.
In the morning he goes downhill to one station and in the afternoon he goes downhill from the other station to his home.

Lift Jacob, any one can do it except Jacob himself.

4 dogs. Each dog sits opposite of the three other dogs. And they sit on each others tails (it is a small room)

Looking at the exact text this problem isn’t solvable.
The problem says: “The sum of the three digits equals 36 times of the number“.
The sum of the digits is at most 27 (3 times 9) which is always less than 36 times the lowest 3 digit number (36 * 100).

When the condition is “The number equals 36 times the sum of the three digits” then you get the solution dyj mentioned.
This condition only has two numbers that meets the condition: 324 and 648.
648 does not meet the other two conditions. So we only needed one of these two conditions to find 324 as the answer.