a)

$\frac{{\sout{8}}^4}{{\sout{9}}^3}\cdot \frac{{\sout{3}}^1}{{\sout{14}}^7}=$   $\frac{4}{21}$  

$\frac{{\sout{12}}^1}{23}\cdot \frac{13}{{\sout{24}}^2}=$   $\frac{13}{46}$  

b)

${\sout{12}}^3\cdot \frac{3}{{\sout{16}}^4}=$