Avineyard owner hires 25 people to harvest grapes. the vineyard covers 30 acres. the harvest takes 9 days to complete. a neighbour has a vineyard measuring 20 acres and needs his harvest finished in 5 days. assuming all people work at the same rate, how many people should he hire?

show working out.

30 people

In the first vineyard, it needs 25 people working for 9 days to finish 30 acres of vineyard. Using this information you can determine the worker speed. The number of worker and days were given will increase the speed, but the area of the vineyard will decrease it. The calculation would be:

Worker speed= worker number * times given / vineyard area
Worker speed= 25 people * 9 days / 30 acres = 7.5 people days /acres 

Applying the same calculation into the second vineyard would be:
Worker speed= worker number * times given / vineyard area
7.5 people days /acres = worker number * 5 days / 20 acres
Worker number= (7.5 people days /acres ) / 5 days x 20 acres= 30 people

Igot the answer of 15.8 years.