Question

The approximate distance between town "X" latitude 10 N and town "Y" located on latitude 13 N,is

Answer 1

1 degree of latitude spans 1 nautical mile, so X and Y are 3 nautical miles apart. (assuming they are at the same longitude)

or, you can use whatever units you want, using the formula for arc length
s = rθ
if you know the radius of the earth, and use radians for your θ