Final answer:
Previously cooked foods should be reheated to a temperature of 165°F for 15 seconds within 2 hours to ensure they are safe to consume.
Step-by-step explanation:
When reheating previously cooked foods, the temperature they should reach within 2 hours is 165°F for 15 seconds. This temperature is sufficient to kill any potential bacteria present in the food, ensuring it is safe to consume. If the food has been stored at room temperature, which is generally around 68°F, for more than two hours, it is not considered safe because bacteria may have grown to dangerous levels, and simply reheating the food well may not be enough to make it safe.