Sečtěte a odečtěte zlomky

a)   \[ \frac{1}{6} + \frac{1}{10} + \frac{1}{12} = \]

b)   \[ \frac{4}{9} + \frac{1}{4} - \frac{1}{6} = \]

c)   \[ \frac{2}{5} + \frac{1}{6} - \frac{1}{15} = \]

d)   \[ \frac{2}{9} + \frac{1}{6} - \frac{1}{12} = \]

e)   \[ \frac{1}{6} + \frac{1}{5} - \frac{2}{15} = \]

f)   \[ \frac{3}{10} + \frac{1}{8} - \frac{2}{5} = \]