How Subtraction Works

This is the very beginning of understanding how subtraction works.

Let's look at this set:

5 triangles

Count how many triangles
are in this set...  There are 5!

Now, take two triangles away...

5 triangles with 2 being taken out

3 triangles left the 2 triangles that were taken out

 
Count how many triangles are left
in the set...  There are 3 left!		  

So, 5-2=3
1 2 3
of 3