The data set in alcohol contains information on a sample of men in the United States. Two key variables are self-reported employment status and alcohol abuse (along with many other variables). The variables employ and abuse are both binary, or indicator, variables: they take only the value zero and one.

a) Write out the R code to generate a subsample of men who abuse alcohol only.

b) Write out the R code to generate the employment rate of the men who abuse alcohol only.