Answer:
250
Step-by-step explanation:
Number of labourers * Number of days worked = Total number of working days
Total number of working days to construct a 4km long road: 
Total mumber of working days to construct a 8km long road: 
Labourers: 20000 ÷ 80 = 250.
250 labourers are required.
As an integer and a raitonal number as well as a real number.
1,234
One thousand
Two hundred
Thirty four