What is -|5-12|?

This is what you start with: -|5-12|
Perform the operation inside the absolute value symbols, which is 5 - 12 = -7.
So the problem becomes: -|-7|
Since the value inside the absolute value symbols must be positive, when you remove the symbols, you are left with 7, but remember the negative sign that preceded it. This makes the answer -7.