Answer:
First of all, the verb estar can be used to express how a person or people are feeling at a certain moment. So the question stands for the simple present because están is the conjugation of the verb estar that matches ustedes in the simple present. Therefore, we can give a reply to this question using the conjugation estamos (matches nosotros). Therefore, we have the following dialogue:
- ¿Cómo están? (How are you all?)
- Estamos enfermos (We are sick)