Hello ,
Explication :
Imagine we have a Labour who works 8h/day and an excavation task ,
the original duration of the task is 10 days
so ,this laber will work a total of 80h ,
If i change the original duration to 2 days ,normally this laber have to work 40h/day => 5 labers/ day
But in the table we have always 8h/day (unit/time) =>one laber only
Thank you