\[\boxed{\mathbf{159.}}\]
\[\textbf{а)}\ \frac{9 \cdot 9 \cdot 9}{10 \cdot 10 \cdot 10} = \frac{729}{1000} = 0,729.\]
\[\textbf{б)}\ \frac{9 \cdot 9 \cdot 9}{10 \cdot 10 \cdot 10} = \frac{729}{1000} = 0,729.\]
\[\textbf{в)}\ \frac{8 \cdot 8 \cdot 8}{10 \cdot 10 \cdot 10} = \frac{512}{1000} = 0,512.\]
\[\textbf{г)}\ \frac{7 \cdot 7 \cdot 7}{10 \cdot 10 \cdot 10} = \frac{343}{1000} = 0,343.\]