Spanish language Q&A Forum

Ok, I meant to ask earlier, but when I heard this same phrase for the third or fourth time while watching "¿Quién mató a Sara?" it just really started bugging me: this seems to be a great example of the impersonal ellos form (the whole premise is that he thinks she was killed but doesn't actually know who did it!) but I can't understand why that "la" is there. "La mataron" or "A Sara Mataron" I get, but how isn't it redundant to have both...? 

If anyone knows what's going on here, thanks in advance for any insight you're willing to offer! (but no spoilers please!) 😂 

Excellent having these examples of pleasantries all in one place.

The third example above is written "Los conciertos de la calle son ruidosísimos."

If so, it seems to violate the rule of taking the masculin form and replacing the "o" with "ísimo".

If not, is it a typo?

Regardless of gender, would you always use un when talking of self?  For instance, Soy un cocinera mala. 

When would be appropriate to use formal and informal second person?

For context, I'm planning to speak mostly with my Mexican family members, many that I'll be meeting for the first time or for the first time in many years. Most of them are older than me (I have one younger brother who speaks mostly Spanish). Would it be better to speak formally to the older family members, or informally because they're family?

Would you start formally with strangers (esp. those who are older) and then at some point be able to drop formality as you become closer to people, or as they express to you that it's okay (similar to Korean and Japanese)?

The choices include c) salgan and d) hayan salido.  Aren't both of these subjunctive? The correct answer was c), salgan. I read through the lesson fairly thoroughly and don't see why hayan salido would not be correct as well. What am I missing? Thanks!