Question

There are 5ppl in a room. you go in that room and kill 4 of those 5ppl. how many ppl actually remain in that room

Answer 1

To come means you were at a place and went over to this place.

This means that there was originally 5 people in a room. You came into the room and murdered 4 of them.

‘How many’ refers to how many of those people in that room originally are left. 

You won't count yourself because you weren’t there originally.

So that means the answer to your question is 1 person.