Quelqu'un peut m'aider svp !!

If 10 men take 18 days to mow 60 acres of grass, how long will 15 men take to mow 80 acres?

Given f(x)= 9x+1 and g(x)=x^3, choose the expression (f*g)(x)

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 25, a standard deviation of 2.5, and margin of error of 5%