4257 Вычислите: a) $$ -4\frac{1}{3} - (-\frac{7}{9}); $$ б) $$ 5\frac{2}{7} - 6\frac{5}{14}; $$

a) $$-4\frac{1}{3} - (-\frac{7}{9}) = -\frac{13}{3} + \frac{7}{9} = -\frac{39}{9} + \frac{7}{9} = -\frac{32}{9} = -3\frac{5}{9}$$. б) $$5\frac{2}{7} - 6\frac{5}{14} = \frac{37}{7} - \frac{89}{14} = \frac{74}{14} - \frac{89}{14} = -\frac{15}{14} = -1\frac{1}{14}$$.