Answer:
Original number of days were 40.
Explanation:
We know that,
The factory produced 70 items in one day.
So, items produced in 'x' number of days =

After hiring 3 more people, the factory produced 10 more items daily and completed the work 5 days before the schedule.
That is, the factory produced 80 items in one day.
Then, items produced in 'x-5' number of days =

So, we get,

i.e.

i.e.

i.e. x= 40.
Hence, the number of days to complete the work originally were 40.