$a)3\cdot \frac{7}{8}=\frac{3\cdot 7}{8}=\frac{21}{8}=2\frac{5}{8}$  

$b)\frac{8}{7}\cdot 3=\frac{8\cdot 3}{7}=\frac{24}{7}=3\frac{3}{7}$

$c)2\cdot 1\frac{1}{7}=2\cdot \frac{8}{7}=\frac{2\cdot 8}{7}=\frac{16}{7}=2\frac{2}{7}$

$d)2\frac{1}{5}\cdot 3=\frac{11}{5}\cdot 3=\frac{33}{5}=6\frac{3}{5}$

$e)5\cdot 10\frac{1}{2}=5\cdot \frac{21}{2}=\frac{5\cdot 21}{2}=\frac{105}{2}=52\frac{1}{2}$

$f)10\cdot 8\frac{2}{3}=10\cdot \frac{26}{3}=\frac{260}{3}=86\frac{2}{3}$

$g){\sout{5}}^1\cdot \frac{7}{{\sout{10}}^2}=\frac{7}{2}=3\frac{1}{2}$

$h)\frac{2}{{\sout{7}}^1}\cdot {\sout{14}}^2=4$

$i)\frac{2}{{\sout{18}}^3}\cdot {\sout{12}}^2=\frac{4}{3}=1\frac{1}{3}$

$j)4\cdot 5\frac{5}{12}={\sout{4}}^1\cdot \frac{65}{{\sout{12}}^3}=\frac{65}{3}=21\frac{2}{3}$

$k)6\frac{2}{8}\cdot 6=6\frac{1}{4}\cdot 6=\frac{25}{{\sout{4}}^2}\cdot {\sout{6}}^3=\frac{25\cdot 3}{2}=\frac{75}{2}=37\frac{1}{2}$

$l)3\cdot 5\frac{5}{6}={\sout{3}}^1\cdot \frac{35}{{\sout{6}}^2}=\frac{35}{2}=17\frac{1}{2}$