Lan commutes to work each day on the highway. She noticed that when she is in a construction zone, her average speed is one-third that of her average speed during typical driving conditions.

One day, Lan travels 20 miles in construction zones and the rest of the trip is at her typical speed. Her total travel time for this
day is represented by the expression below.

Select the term in the expression that represents Lan's typical average speed.

20/30 + 30/3x