[tex] a) \frac{1}{4} - \frac{2}{8} = \frac{1}{4} - \frac{1}{4} = 0 \\ \\ b) \frac{2}{15} + \frac{3}{30} = \frac{2}{15} + \frac{1}{10} = \frac{2 \times 2}{15 \times 2} + \frac{1 \times 3}{10 \times 3} = \frac{4}{30} + \frac{3}{30} = \frac{4 + 3 }{30} = \frac{7}{30} \\ \\ c) \frac{4}{25} - \frac{8}{30} = \frac{4}{25} - \frac{4}{25} = 0 [/tex]
