2 3 − 3 4 3 5 − 3 4 {\displaystyle {\dfrac {\ {\frac {2}{3}}-{\frac {3}{4}}\ }{{\frac {3}{5}}-{\frac {3}{4}}}}} = 2 3 − _ 3 4 3 5 − _ 3 4 = 2 ⋅ 4 − 3 ⋅ 3 3 ⋅ 4 3 ⋅ 4 − 5 ⋅ 3 5 ⋅ 4 = − 1 12 − 3 20 = − 1 12 : − 3 20 = − 1 12 3 ⋅ 20 5 − 3 = 5 9 {\displaystyle ={\dfrac {\ {\frac {2}{3}}{\underline {\xcancel {-}}}{\frac {3}{4}}\ }{{\frac {3}{5}}{\underline {\xcancel {-}}}{\frac {3}{4}}}}={\dfrac {\ \ {\frac {2\cdot 4-3\cdot 3\ \ }{3\cdot 4}}}{\frac {3\cdot 4-5\cdot 3}{5\cdot 4}}}={\dfrac {\ \ {\frac {-1}{12}}\ \ }{\frac {-3}{20}}}={\frac {-1}{12}}:{\frac {-3}{20}}={\frac {-1}{\cancelto {3}{12}}}\cdot {\frac {\cancelto {5}{20}}{-3}}={\frac {5}{9}}}
