Demo

b_ = Bb/A#

Notes

    c d f, g a e dcd
    f g a, C D f g ab_a
    a C D C D, d a g, f g
    gac, d e g a d f
    
    C C D F E, D C D
    C C D F E, D C a
    c d f, g a e dcd
    f g a, C D f g ab_a
    a C D C D, d a g, f g
    gac, d e g a d f