Final answer:
If the given system has no solution, the value of a/b is undefined.
Step-by-step explanation:
If the given system of equations has no solution, then it means that the lines represented by the equations are parallel and will never intersect. In this case, the value of a/b is undefined. This is because when the system has no solution, it implies that the coefficient of x in both equations should be the same (equal to a), but in this case, it is different (1 and -1). Therefore, the value of a/b is D. a/b = Undefined.