5.88 Упростите выражение: a) \(\frac{1}{27}a - \(\frac{4}{9}a - \frac{1}{3}a\)\); б) \(\frac{5}{7}(\frac{7}{5}a - 7) - 9(2\frac{1}{3}a + \frac{5}{9})\);

а)

\[\frac{1}{27}a - \left(\frac{4}{9}a - \frac{1}{3}a\right)\]

\[\frac{1}{27}a - \frac{4}{9}a + \frac{1}{3}a = \frac{1}{27}a - \frac{12}{27}a + \frac{9}{27}a = \frac{1 - 12 + 9}{27}a = -\frac{2}{27}a\]

Ответ: \(-\frac{2}{27}a\)

б)

\[\frac{5}{7}\left(\frac{7}{5}a - 7\right) - 9\left(2\frac{1}{3}a + \frac{5}{9}\right)\]

\[= \frac{5}{7} \cdot \frac{7}{5}a - \frac{5}{7} \cdot 7 - 9 \cdot \frac{7}{3}a - 9 \cdot \frac{5}{9}\]

\[= a - 5 - 21a - 5 = -20a - 10\]

Ответ: \(-20a - 10\)