The total distance John travelled can be obtained by finding the sum of the distances between two consequtive points.
The expression for the distance between two points is,
Here, (x1, y1) and (x2,y2) are the coordinates of two points.
Given, A(0,4), B(4,1), C(3,-1) and D(-1,2) are the coordinates of cities.
The distance beween A(0,4) and B(4,1) is,
The distance beween B(4,1) and C(3,-1) is,
The distance beween C(3,-1) and D(-1,2) is,
The distance beween A(0,4) and D(-1,2) is,
Now, the total distance John traveled is,
Therefore, the total distance John traveled rounded to the nearest tenth is 14.5 units.