Initial distance from which Harry starts to walk (x1) = - 14 meter
Final distance up to which Harry walks (x2) = - 52 meter
Time taken by Harry to walk from x1 to x2 = 38 second
Then
Velocity = (x2 - x1)/Time taken
= [- 52 - (-14)]/38 meter/second
= (-52 + 14)/38
= -(38/38) meter/second
= -1 meter/second.
So the velocity at which Harry walks is -1 meter per second. Hope you are satisfied with the procedure and the procedure is also clear enough for you.