[tex]\it (5\dfrac{3}{5}-1\dfrac{1}{3}):(7\dfrac{7}{12}-2\dfrac{1}{4})=(\dfrac{^{3)}28}{5}-\dfrac{^{5)}4}{3}):(\dfrac{91}{12}-\dfrac{^{3)}9}{4})=\dfrac{84-20}{15}:\dfrac{91-27}{12}=\\ \\ \\ =\dfrac{64}{15}:\dfrac{64}{12}=\dfrac{\not64}{15}\cdot\dfrac{12}{\not{64}}=\dfrac{12^{(3}}{15}=\dfrac{4}{5}[/tex]
