Which pair of functions are inverses of each other?

How far is x from 5 on a number line?

Use set builder notation to represent the following set: { -3, -2, -1, 0}

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?