Hello

I have just started to play guitar. And am working on the Minor Pentatonic scales at the moment and have a question about it.
I have currently learnt all the positions on the fret board and now I want to try a bit of soloing to work on my finger work.

The question is when playing the Minor Pentatonic Scale or any other scale for that matter, how do you know what scale to play for what key?

For example if a song is in the key of A Major what scale to use. Or if the song is in the Key of C # what scale to use. Could you still use the minor pentatonic for these keys or do you need to use something else.

Is there a pattern you follow to know what types of scales fit over certain keys?

Thanks