Final answer:
The crew will complete 81.6 square feet after 12 hours.
Step-by-step explanation:
To find the number of square feet the crew will complete after 12 hours, we can multiply the number of square feet they complete in one hour (6.8 square feet) by the number of hours they work (12 hours).
Using the multiplication operation, we have:
6.8 square feet/hour * 12 hours = 81.6 square feet
Therefore, the crew will complete 81.6 square feet after 12 hours.