Answer
$$\frac{1}{12}.$$
Work Step by Step
We simplify by removing the parenthesis and add the terms as follows:
$$
\frac{-3}{16}\div \left( -2\frac{1}{4} \right)= \frac{-3}{16}\div \frac{-9}{4}\\
=\frac{-3}{16} \cdot \frac{4}{-9}=\frac{1}{12}.$$
