[tex]( \frac{2}{3} + \frac{1}{4}) - ( \frac{1}{10} + \frac{1}{4} ) = \\ \\ ( \frac{8 + 3}{12} ) - ( \frac{2 + 5}{20} ) = \frac{11}{12} - \frac{7}{20} = \frac{5}{9} .[/tex]
