Given :
On a map's coordinate grid, Milton City is located at (-4,-3) and McDanielsville is located at(4, -9).
To Find :
How long is a train's route as the train travels along a straight line from Milton City to McDanielsville .
Solution :
We need to find the distance between points (-4,-3) and (4,-9) .
Now , distance between two points (x,y) and (a,b) is given by :

For points (-4,-3) and (4,-9) distance between them is :

Therefore , distance travelled by train is 10 units .
Hence , this is the required solution .