[tex]\frac{1}{2} + \frac{2}{4} - \frac{4}{12} = \frac{2}{4} + \frac{2}{4} - \frac{4}{12} = \frac{4}{4} - \frac{4}{12} = \frac{12}{12} - \frac{4}{12} = \frac{8}{12} = \frac{2}{3}[/tex]
