Let

$$ Pages\quad sold\quad by\quad Carlos=1 $$

Then given that Mary sold twice pages as Carlos:

$$ Pages\quad sold\quad by\quad Mary=2 $$

And given that James sold pages 3 times as Mary:

$$ Pages\quad sold\quad by\quad James=6 $$

So

$$ Total\quad pages=9 $$

and

$$ Fraction\quad of\quad pages=\frac{1}{9} $$