Answer
a
Work Step by Step
We find:
$$ \frac{ \triangle}{ \square}\div \frac{ \circ}{\triangle}$$
We flip around the second fraction and multiply:
$$ \frac{ \triangle}{ \square} \times \frac{\triangle}{\circ}$$
This gives:
$$ \frac{\triangle \triangle}{ \square \circ }$$
This matches $\underline{a}.$
