Given:
Eric has planted corn on 480 acres
Eric can harvest 80 acres per day
We will find the number of days to harvest 480 acres
so, we will divide 480 by 80
so, the number of days =

So, it will take 6 days to harvest with the harvesting machine or combine
And if Eric had 2 combines, so, it will take the half time
So, for 2 combines, the number of days = 6/2 = 3 days
so, the answer will be:
6 days to harvest 480 acres
3 days using 2 combines