Veronica’s velocity was measured as 4.3 m/s. She displaced 20 meters in 4.7 seconds. Which piece of information is missing for the correct...

Velocity of an object is a vector quantity, unlike speed (which is scalar) and is the ratio of displacement to time taken. In other words,

velocity = displacement of the body / time taken for the displacement

In comparison, speed is the ratio of distance traveled to time taken.

In this case, it is given that Veronica had a displacement of 20 m and the time taken for displacement was 4.7 seconds. Since the velocity is a vector quantity, we need the direction of the motion. Veronica may have moved in a straight line or moved in a circle or went 10 m and then came back. In all these cases, effective displacement would be different. 

Thus, without the direction of the motion, we cannot calculate Veronica's velocity.

Hope this helps.