We have looked at situations in which we need to determine the number of possible routes between two places. We can look at the situation below as 9 steps, six of which must be East and three of which must be South.
This gives us 9!/3!6! possible routes.
The calculation is equivalent to 9C3 (or 9C6).
Explain clearly why you could solve this question using combinations, and why this is equivalent to considering permutations with repeated items.