$\frac{4\ast <!--\; \ast \; -->3}{27\ast <!--\; \ast \; -->8}=\frac{\stackrel{1}{\bcancel{4}}\ast <!--\; \ast \; -->\stackrel{1}{\bcancel{3}}}{\underset{9}{\bcancel{27}}\ast <!--\; \ast \; -->\underset{2}{\bcancel{8}}}=\frac{1}{18}$

$\frac{12\ast <!--\; \ast \; -->14}{35\ast <!--\; \ast \; -->15}=\frac{\stackrel{4}{\bcancel{12}}\ast <!--\; \ast \; -->\stackrel{2}{\bcancel{14}}}{\underset{5}{\bcancel{35}}\ast <!--\; \ast \; -->\underset{5}{\bcancel{15}}}=\frac{8}{25}$

$\frac{17\ast <!--\; \ast \; -->22}{55\ast <!--\; \ast \; -->34}=\frac{\stackrel{1}{\bcancel{17}}\ast <!--\; \ast \; -->\stackrel{2}{\bcancel{22}}}{\underset{5}{\bcancel{55}}\ast <!--\; \ast \; -->\underset{2}{\bcancel{34}}}=\frac{2}{10}=\frac{1}{5}$

$\frac{12\ast <!--\; \ast \; -->14}{35\ast <!--\; \ast \; -->15}=\frac{\stackrel{4}{\bcancel{12}}\ast <!--\; \ast \; -->\stackrel{2}{\bcancel{14}}}{\underset{5}{\bcancel{35}}\ast <!--\; \ast \; -->\underset{5}{\bcancel{15}}}=\frac{8}{25}$

$\frac{8\ast <!--\; \ast \; -->13\ast <!--\; \ast \; -->45}{15\ast <!--\; \ast \; -->24\ast <!--\; \ast \; -->39}=\frac{\stackrel{1}{\bcancel{8}}\ast <!--\; \ast \; -->\stackrel{1}{\bcancel{13}}\ast <!--\; \ast \; -->\stackrel{3}{\bcancel{45}}}{\underset{1}{\bcancel{15}}\ast <!--\; \ast \; -->\underset{3}{\bcancel{24}}\ast <!--\; \ast \; -->\underset{3}{\bcancel{39}}}=\frac{3}{9}=\frac{1}{3}$

$\frac{9\ast <!--\; \ast \; -->14+9\ast <!--\; \ast \; -->5}{18\ast <!--\; \ast \; -->38}=\frac{9\ast <!--\; \ast \; -->(14+5)}{18\ast <!--\; \ast \; -->38}=\frac{9\ast <!--\; \ast \; -->19}{18\ast <!--\; \ast \; -->38}=\frac{\stackrel{1}{\bcancel{9}}\ast <!--\; \ast \; -->\stackrel{1}{\bcancel{19}}}{\underset{2}{\bcancel{18}}\ast <!--\; \ast \; -->\underset{2}{\bcancel{38}}}=\frac{1}{4}$

$\frac{15\ast <!--\; \ast \; -->21}{15\ast <!--\; \ast \; -->32-<!--\; -\; -->15\ast <!--\; \ast \; -->4}=\frac{15\ast <!--\; \ast \; -->21}{15\ast <!--\; \ast \; -->(32-<!--\; -\; -->4)}=\frac{15\ast <!--\; \ast \; -->21}{15\ast <!--\; \ast \; -->28}=\frac{\stackrel{1}{\bcancel{15}}\ast <!--\; \ast \; -->\stackrel{3}{\bcancel{21}}}{\underset{1}{\bcancel{15}}\ast <!--\; \ast \; -->\underset{4}{\bcancel{28}}}=\frac{3}{4}$

$\frac{42\ast <!--\; \ast \; -->17-<!--\; -\; -->16\ast <!--\; \ast \; -->17}{51\ast <!--\; \ast \; -->7+51\ast <!--\; \ast \; -->6}=\frac{17\ast <!--\; \ast \; -->(42-<!--\; -\; -->16)}{51\ast <!--\; \ast \; -->(7+6)}=\frac{17\ast <!--\; \ast \; -->26}{51\ast <!--\; \ast \; -->13}=\frac{\stackrel{1}{\bcancel{17}}\ast <!--\; \ast \; -->\stackrel{2}{\bcancel{26}}}{\underset{3}{\bcancel{51}}\ast <!--\; \ast \; -->\underset{1}{\bcancel{13}}}=\frac{2}{3}$