Please do not ask for more details as an answer because that area is reserved for direct answers to the question.
The 50 point reputation requirement is there for the reasons discussed in Why do I need 50 reputation to comment? What can I do instead? so I recommend reading that Q&A and following the advice in its only, and highly upvoted, answer.
I think the best way to get to 50 points quickly is to ask a few good questions and I recommend the collective advice on how to do that here which is documented in Asking good Questions for GIS Stack Exchange? at GIS SE.
If you prefer to try and get there via answers rather than questions then in the particular instance you cite, if there is not enough information to be certain of whether you are answering the question they are trying to ask, but you think you know, then just state some assumptions you are making and provide the answer. However, I would recommend not going too far out on a limb when you do this.
As noted in @AndreSilva's answer you can get to 50 more incrementally by suggesting edits to posts (try to make them substantial) because if they are approved each gets you two points.
... another way to acquire the privilege of commenting. From our help
pages, "If you
are an experienced Stack Exchange network user with 200 or more
reputation on at least one site, you will receive a starting +100
reputation bonus to get you past basic new user restrictions. This
will happen automatically on all current Stack Exchange sites where
you have an account, and on any other Stack Exchange sites at the time
you log in."