If the tension in the cable supporting an elevator equals the...

Let $T$ be the tension in the cable and $mg$ be the weight of the elevator.

The net force acting on the elevator is $F_{net} = T - mg$.

Given that $T = mg$, we get $F_{net} = 0$.

By Newton's second law, $F_{net} = ma$, so the acceleration of the elevator is $a = 0$.

Zero acceleration implies that the elevator is either at rest or moving with a uniform velocity.

Thus, the elevator may be moving downward with uniform speed or moving upward with uniform speed.