uh ans key says the ans is 4 tho

The method to do this qn is based on the distance each man can cover in 60 days. Using the rate to calculate the total number of men required and finding the additional number of men required.

4 should not be the answer. To elaborate further on this, if 30 men takes 30 days to build 1km. For the remaining 60 days, 30 men will only be able to build 2km more. Which means that the additional number of men needs complete 1km in 60 days. So the question is, can 4 men complete 1km in 60 days assuming the rate each men build the road remains the same? Hopefully you get the explanation!

Glad to help!

ohhhhhhh okay I understand, tysm