25. \(\left(6\frac{8}{15}-4\frac{26}{45}\right)\cdot4,5-\frac16:0,52\)

\(6\frac{8}{15}-4\frac{26}{45}=\frac{294}{45}-\frac{206}{45}=\frac{88}{45}\).

\(\frac{88}{45}\cdot4.5=\frac{88}{45}\cdot\frac92=\frac{44}{5}\).

\(\frac16:0.52=\frac16:\frac{13}{25}=\frac{25}{78}\).

\(\frac{44}{5}-\frac{25}{78}=\frac{3307}{390}\).

Ответ: \(\frac{3307}{390}\)