So, when you have something like - ( - 2x), the first "-" changes the whole expression inside the brackets, so it becomes 2x (potitive).

My question is: when I have + (-2x), does it also change?...My opinion is that it does not change, and I am quite sure of that, but I have an excercise that says the following (its a fraction):

- sen x
+ (-------------)
- cos x - 1

and in the following step in this excercise, it becomes the following:

sen x
------------
cos x + 1

Can someone pless explain to me how that is achieved?
Thanks.