Answer:
11.66 units
Explanation:
Given that he walks 10 blocks north and then 6 blocks west..
When combined with the straight line to the school, this forms a right angled triangle with the straight line as the hypotenuse.
Hence, let the straight line be h
h^2 = 10^2 + 6^2 (using Pythagoras theorem)
h^2 = 100 + 36
h^2 = 136
h = √ 136
h = 11.66 units