Answer:
1.) <em>Paulina y Esteban </em><em><u>están</u></em><em> en el estadio, ¿no?</em>
2.) <em>Yo </em><em><u>estoy</u></em><em> en casa. </em>
3.) <em>Hola, Mónica. ¿Cómo </em><u><em>estás</em></u><em>?</em>
Explanation:
These are all forms of the verb to be, in the form "estar" which is used for conditions, locations, emotions, and actions (temporary states).
You have to adapt it accordingly to the person in the sentence you're referring to (conjugation)
1.) <em> </em>están - conjugated with "ellos" (they)
2.) estoy - conjugated with "yo" (I)
3.) estás - conjugated with "tú" (you)
