Answer: 200 pairs
Explanation:
The store made a profit of $9,000 - $5,000 = $4,000.
Since they made a profit of $20 per pair of sunglasses, we can divide the total profit by $20 per pair to find out how many pairs of sunglasses were involved.
So, the number of pairs of sunglasses is $4,000 / $20 = 200 pairs.