[tex] \dfrac{5}{9} \times \dfrac{27}{10} - \dfrac{1}{2} = \dfrac{ 5\times 27 }{9\times 10}^{\Big{\backslash 5}} - \dfrac{1}{2} = \dfrac{27}{9\times 2}- {^{\Big{ 9\slash}}\dfrac{1}{2} = \dfrac{27}{9\times 2}- \dfrac{9}{9\times 2}} = \\ \\ = \dfrac{27-9}{9\times 2} = \dfrac{18}{18}=1 [/tex]
