If two lines are parallel, their slopes will be equal. If they are perpendicular, the slope of the first line multiplied by the slope of the second line will equal 1. If they are neither, they won't have any special relationship.
Line A:
Slope = (7 - 5)/(0 - -3), which is equal to 1/3
Line B:
Slope = (4 - 2)/(9 - 6), which is also equal to 1/3.
The two slopes are the same, therefore they are parallel.
