He then went to see the oranges being harvested. He found out that they harvested 17 sacks of oranges. How many days did it take to harvest them if they harvested 1 sacks of oranges per day?
1. He went to see the oranges being harvested. 
2. He found out that they harvested 17 sacks of oranges. 
3. How many days did it take to harvest them if they harvested 1 sacks of oranges per day?

So, we need to find out how many days it took to harvest 17 sacks of oranges. 

We can set up a proportion: 

17 sacks of oranges / 1 sack of oranges per day = x days

We can solve for x: 

17 sacks of oranges / 1 sack of oranges per day = x days
17 sacks of oranges = 1 sack of oranges per day * x days
17 sacks of oranges = x days

It took 17 days to harvest 17 sacks of oranges.