The relative minor is the sixth note of the major scale.
Or you can count back three frets on the guitar.
Well we all shine on--like the moon and the stars and the sun.
-- John Lennon
The relative minor is built on the 6th degree of the major scale (1 whole step higher than the 5th if that helps).
In C major, A is the 6th, 2 frets higher than the 5th, G.
Backwards, the major is the flat 3rd of the minor. In A major, C is the b3, 3 frets up.
It becomes 2nd nature eventually.
Look at this partial neck diagram.
M is the major, m is the relative minor (6th), 5 is the 5th (of the major).
--|-----|-----|--m--|-----|-----|--M--|-----|-----|
--|-----|-----|-----|-----|-----|--5--|-----|--m--|
--|--m--|-----|-----|--M--|-----|-----|-----|-----|
--|-----|-----|-----|--5--|-----|--m--|-----|-----|
--
Helgi Briem
hbriem AT gmail DOT com