It is about :
Length of line segment in the rectangular coordinate system

If a segment is horizontal, its length is the difference between its x coordinates. If the result is negative, you need to consider the absolute value (or just pick the coordinates in the correct order, i.e. the bigger minus the smaller).

So, we have

they will manufacture 8496 cars

answer: both chords and diameters have two endpoints on a circle. diameters must intersect the center of a circle.