Ответ:
\[\left(-\frac{5}{7}\right)\cdot\left(-\frac{49}{25}\right)=\frac{7}{5},\qquad a^2\cdot a^4=a^6,\qquad b^2\cdot b=b^3.\]
Ответ: \(\boxed{\frac{7}{5}a^6b^3}\).
\[\left(-\frac{5}{7}\right)\cdot\left(-\frac{49}{25}\right)=\frac{7}{5},\qquad a^2\cdot a^4=a^6,\qquad b^2\cdot b=b^3.\]
Ответ: \(\boxed{\frac{7}{5}a^6b^3}\).