Highschool Physics pt. 2: Distance and displacement introduction

 Let's take a sheep, a small innocent sheep, and let's watch as it follows and eats the grass. And let's watch it as it travels 10km east, and 5km south, and then another 10km west.

Now depending on how you interpret the movement of the sheep, there are two reasonable answers, one is it's "Distance Traveled", to do this equation it is 10km + 5km + 10km, which would be 25km. As you are adding all the numbers together.

Now if you wanted to find the "Displacement", the 10km east, and the 10km, west would cancel out. And that would leave the sheep 5km south from where it started. 

Ok what about a number line, lets say an orange, starts off at 0, and rolls to point 2, so that's a +2 to the right, and then lets say it rolls -3 to the left, and another -1 to the left. 
So for distance travel, you are going to add all the number up, reguardless of the minus or plus, so the distance travelled is 6 (2+1+3). 
But what happens if you want to find displacement well then the answer is -2 (0+2-1-3).