Answer:
15 km
Explanation:
We can use the Pythagorean theorem to solve
a^2 + b^2 = c^2
Draw a triangle with 12 for x direction and 9 for y direction
The distance is the connecting line which is the hypotenuse
12^2 + 9^2 = c^2
144+81 = c^2
225 = c^2
Taking the square root of each side
sqrt(225) = sqrt(c^2)
15 =c