Answer:
1. Ellas. (two people, both female, the speaker is not included in the group, so the female they form is correct.)
2. Ellos. (Two people, one male, one female. If there is at least one male, then the pronoun is male.)
3. Ellas. (Same as #1.)
4. Nosotros. (Includes the speaker and the person the speaker is speaking to-nosotros means we and there is a masculine name so it's in masculine form.)
5. El. (means he.)
6. Nosotros. (Includes speaker. Is in masculine form because when gender is not specified, you always go with masculine.)
7. Ellas. (Same as #1)
8. vosotros or ustedes. (the speaker is addressing people directly. Basically saying ya'll, which is what vosotros and ustedes mean.)
9. Ella. (one female, means she.)
10. Ellos. (a group of people that doesn't include the speaker or the person the speaker is speaking to. Masculine form because gender is not specified.)
11. Ellos. (two people, not including speaker or listener, one boy so masculine form.)
12. Nosotros. (Includes speaker and others, so it would be we, which is what nosotros means. Masculine form because gender is not specified.)
13. vosotros or ustedes. (group including listener, so the speaker would refer to the group as ya'll, or you all. Masculine form because gender is not specified.)
14. vosotros or ustedes. (I would go with ustedes because it's more formal, and usted is the formal version of you.)
15. Ellas. (referring to a group of people not including the speaker or listener. Female form because there is las in the question, which means only females.)
16. Ellos. (Same as #10.)
17. Ellas. (Same as #15)
18 Ellos. (Same as #10)
19. Ellas. (Same as #1)
20. Ellos. (Both masculine because of the los.)
Hope this helps :)
