Use the appropriate formula to evaluate each function.
$\begin{array}{l}
\sin \left(\frac{7 \pi}{6}-\frac{\pi}{3}\right)=\square \\
\cos \left(105^{\circ}\right)=\square \text { (Hint: Use a sum formula) } \\
\tan \left(\frac{\pi}{6}-\frac{\pi}{4}\right)=\square
\end{array}$
$\begin{array}{l}
\sin \left(\frac{7 \pi}{6}-\frac{\pi}{3}\right)=\square \\
\cos \left(105^{\circ}\right)=\square \text { (Hint: Use a sum formula) } \\
\tan \left(\frac{\pi}{6}-\frac{\pi}{4}\right)=\square
\end{array}$