${\displaystyle \frac{1}{x}}+2={\displaystyle \frac{9}{x}}\backslash dfrac1x+2=\backslash dfrac9x$

${\displaystyle \frac{2x+4}{8}}={\displaystyle \frac{8x-7}{20}}\backslash dfrac\{2x+4\}8=\backslash dfrac\{8x-7\}\{20\}$

${\displaystyle \frac{2}{9}}\cdot {\displaystyle \frac{x}{11}}={\displaystyle \frac{27}{22}}\backslash dfrac29\backslash cdot\backslash dfrac\; x\{11\}=\backslash dfrac\{27\}\{22\}$

$\frac{15}{x}\cdot \frac{12}{21}=6\backslash frac\{15\}x\backslash cdot\backslash frac\{12\}\{21\}=6$