Answer:
4. esta
5. estoy
6. estan
Explanation:
4. esta is "estar" but with "usted/ella/ello" conjugation. you family counts as "usted, ella, ello"
5. estoy is "estar" but with "yo" conjugation. your books are yours therefore you need to use the "yo" conjugation
6. estan is "estar" but with "ustedes/Ellas/Ellos" conjugation. you are talking about two people, they are referred to as they (ellas/ellos is they/them in spanish).
