Suppose the labour demand faced by a monopsonist firm is W = 40,000 - 100/, where W is the annual wage (i.e. salary) and ! is the number of workers hired. The labour supply is W = 10,000 + 100/, Derive an expression for marginal expenditure and determine the annual wage the monopsonist would pay and how many workers it would hire. Show this in a fully labelled diagram