Hi!
The relation between major and minor scales is probably best hinted in the circle of fifths:
en.wikipedia.org
For each major scale there is a relative minor scale which share same notes but starting from different root note. Based on the circle
en.wikipedia.org you may find that A (major) is relative to F♯m (minor), etc. This is theory based on classical key notation.
The 3A, 4A, 4B is alternative key notation called Camelot which identifies these relations in much easier way, see the picture on this page:
serato.com
Basically key in A (major) in classical notation would become 11B in camelot notation and its relative minor would be 11A (again F♯m in classical notation).
If you'd like to go deeper into musical key theory, I recommend starting with "Fundamentals of Music Theory" Coursera online course. If you just quickly need to find a relative key, then save
one of those circle images as a cheat sheet, that should be good enough.
