Question

the length of the fish a fisherman catches, ( l ), must be at least 10 inches for him to keep it.

Explanation:

Step1: Define variable condition

Let $l$ = fish length (in inches). The length must be at least 10 inches, meaning $l$ is greater than or equal to 10.
<Expression>
$l \geq 10$
</Expression>

Answer:

$l \geq 10$