$a)\frac{{\sout{3}}^1}{7}\cdot \frac{5}{{\sout{9}}^3}=\frac{1}{7}\cdot \frac{5}{3}=\frac{5}{21}$  

$\frac{{\sout{4}}^1}{3}\cdot \frac{7}{{\sout{16}}^4}=\frac{1}{3}\cdot \frac{7}{4}=\frac{7}{12}$  

$\frac{{\sout{6}}^2}{11}\cdot \frac{5}{{\sout{9}}^3}=\frac{2}{11}\cdot \frac{5}{3}=\frac{10}{33}$  

$b)\frac{{\sout{8}}^2}{{\sout{21}}^3}\cdot \frac{{\sout{7}}^1}{{\sout{12}}^3}=\frac{2}{3}\cdot \frac{1}{3}=\frac{2}{9}$    

$\frac{{\sout{5}}^1}{{\sout{6}}^2}\cdot \frac{{\sout{9}}^3}{{\sout{20}}^4}=\frac{1}{2}\cdot \frac{3}{4}=\frac{3}{8}$  

$\frac{{\sout{4}}^1}{{\sout{7}}^1}\cdot \frac{{\sout{21}}^3}{{\sout{36}}^9}=\frac{3}{9}=\frac{1}{3}$  

 

$c)1\frac{1}{3}\cdot 2\frac{1}{4}=\frac{{\sout{4}}^1}{{\sout{3}}^1}\cdot \frac{{\sout{9}}^3}{{\sout{4}}^1}=3$  

$1\frac{1}{2}\cdot 1\frac{5}{9}=\frac{{\sout{3}}^1}{{\sout{2}}^1}\cdot \frac{{\sout{14}}^7}{{\sout{9}}^3}=\frac{7}{3}=2\frac{1}{3}$  

$2\frac{5}{8}\cdot 1\frac{1}{3}=\frac{{\sout{21}}^7}{{\sout{8}}^2}\cdot \frac{{\sout{4}}^1}{{\sout{3}}^1}=\frac{7}{2}=3\frac{1}{2}$