Day 1 day: 12-3=9 (day) is left. It takes 9- 1=8 (day) to give a worker a day's food.
The next day: there are 8-2=6 (days) left to take back to the workers. 6-2=4 (days)
Day 3: 4- 1=3 (days)
Day 4: 3- 1=2 (days)
Day 5: 2- 1= 1 (days)
Day 6: 1
It's done!
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