Mark in the Caribbean asked, “One question, how many scales there are 12 or 15?”

To your ear, there are 12 scales.  They can be written in different ways though.

You could write a C# scale or a Db scale and it would sound the same, but it would be written differently.  Same with F# and Gb.

The are three scales that are somewhat commonly written in different ways which would make it seem like there are 15, but C# sounds the same as Db, F# sounds the same as Gb, and Cb sounds the same as B.

You will see them written in different ways depending on the context.  That can make the relationships between scales and chords more clear.

For example, there is no A# in the F major scale, but there is a Bb.  So if you wanted to show the relationship of a chord to F major, it would be notated as Bb, not A#.  In that way, it is useful to think of there scales in different ways.  And then, visually, there would be 15 (or more) scales.

If you imagined you were playing an A# or Bb, it will still sound the same though.

For me, C# seems more comfortable than Db, so if I see Db major, I might think of C#.

But if you just heard the scales, there would be 12.