Absolute Value symbols (two vertical bars) tell us to evaluate what is inside them, and if the result is negative change its sign before dropping the absolute value symbols.
The answer shown below is wrong. Try working your way through the problem backwards, from the answer up. As you find each mistake, try to identify the thinking behind it… what perspective led to the mistake? What should have been done instead?
Hint 1: the correct answer to the problem on the first line is 5.
Hint 2: more than one mistake has been made, on more than one line.