The answer is 6.
Absolute value works like this:
If you have just a number inside the bars, then it's positive. If the negative sign is inside the bars, it's still positive. If the negative sign is outside the bars, regardless of what's inside the bars, then it's negative.
Basically, you are adding, because absolute values are positive, unless you have a minus sign outside the absolute value, so 6+5=11.
What you do is this:
y = |x - 5|
y = x + 5
y = 11 + 5
y = 6