Final answer:
When you encounter a broken yellow line in the center of the highway, it means that passing on the left is permitted when the way ahead is clear.
Step-by-step explanation:
When you encounter a broken yellow line in the center of the highway, it means that passing on the left is permitted when the way ahead is clear. This means that you are allowed to pass other vehicles on the left side of the broken yellow line as long as there is no oncoming traffic and it is safe to do so. However, crossing the line is prohibited, so you should not cross over the broken yellow line into the opposite lane of traffic.