He then went to see the oranges being harvested. He found out that they harvest w sacks per day and discard x of them. How many oranges do they harvest per day if each sack contains y oranges?
The oranges being harvested per day is w sacks per day. 

The number of oranges being harvested per day is w*y. 

The number of oranges being discarded per day is x. 

Therefore, the total number of oranges being harvested per day is w*y+x.