Step-by-step explanation
Absolute value basically measures how far the number is from zero,for example

as we can see

hence,
Step 1

so, we need to find a number such the distance from zero to that number be zero,
therefore , that number is zero
hence

Step 2

now, weed to find a value such distance from zero is 2, so those values are +2 and -2

Step 3
c)

the solution of a absolute value function is always positive, remeber we are talking about a distance, so, there is not solutioni

I hope this helps you