Answer:

Explanation:
You need to analize the information provided in the exercise.
You know that:
- 20 minutes is the time she waited in thse subway station.
- The time to reach Grand Central Station was
. - And spent
before reaching to work.
Therefore, in order to find the time she took to travel to her office, you need to add the times given in the exercise:
.
Adding the like terms, you get:
