Let’s list a few possible paths, using N to indicate walking one block North and E to indicate walking one block East:
NNNEEEEEEE
NNEEEEEEEN
NENENEEEEE
EEEEEEENNN
… and so on.
This problem then becomes the number of ways of arranging this 10-letter word, or the number of ways of positioning the letter N out of 10 possible spots in a row, which is 10C3= 120.
