To answer this question, we need to know what absolute value is in the first place. ANSWERS ARE AT THE BOTTOM.
Absolute value represents how far something is from 0 in a number line.
For example, lets take 4.
4 is 4 units away from 0 on the number line, so the absolute value of 4 is 4.
Now lets look at another example, -4. -4 is also 4 units away from 0, just in the other direction. However, when calculating absolute value, we do not care about the direction. Therfore, the absolute value of -4 is also 4.
Now let's look at your problem.
You want the absolute value of 0 and -4/5
Following the same principle above about the distance from 0, here are your answers:
Absolute value of 0: 0
Absolute value of -4/5: 4/5