Q. Three whole numbers, greater then zero can be used to form a trio.
example: (1,2,2) is a trio whose sum is 1+2+2=5
And (2,1,2) is a different trio whose sum is also 5
How many trios can you find with a sum of 5?
Since 5 is such a small number, it is easiest just to count all the possibilities.
A trio can't have a 4 or greater, since 4+1+1 = 6 is to ...
This shows how to find how many trios have a sum of 5.