Answer:
2000 years after tomorrow to decompose
Explanation:
it takes 1 disposable diaper to stay for 2000 years to decompose
Then, if you put 4 disposable diapers in a landfill tomorrow, it will take the same 2000 years for them to decompose.
This is because the four diapers are put in the landfill on the same day.
A diaper wouldn't wait for another to finish decomposing before it's starts it's own decomposure.
The four diapers will decompose simultaneously which will take them 2000 years.