What do I need to do

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

Every weekday, mr. jones bikes from his home to his job. sometimes he rides along two roads, the long route that is shown by the solid lines. other times, he takes the shortcut shown by the dashed line. how many fewer kilometers does mr. jones bike when he takes the shortcut instead of the long route?

The distance between two points is 6.5cm and scale of map is 1: 1000 what's the distance between the two points