\[\left( - \frac{4}{15} + \frac{7}{12} \right)\ :\left( - \frac{38}{45} \right) =\]
\[= \left( - \frac{16}{60} + \frac{35}{60} \right)\ :\left( - \frac{38}{45} \right) =\]
\[= \frac{35 - 16}{60}\ :\left( - \frac{38}{45} \right) =\]
\[= - \frac{19 \cdot 45}{60 \cdot 38} = - \frac{3}{8}\]