Final answer:
The inequality symbol used when c is at most 3 is ≤, which means c can be less than or equal to 3. This is represented as c ≤ 3.
Step-by-step explanation:
When stating that c is at most 3, it means that c can be less than or equal to 3, but not more. The inequality symbol that represents this relationship is ≤, which stands for “less than or equal to.” Therefore, the inequality that expresses c is at most 3 is written as c ≤ 3.
To visualize this, you can use a number line where you'd shade all the numbers up to and including the number 3, indicating that any number less than or equal to 3 satisfies the inequality.
An example of this in metric measurements would be if you have a package that has a weight limit of 3 kilograms. The inequality for the maximum weight of the package would be written as weight ≤ 3 kg, meaning the package can weigh 3 kilograms or less.