Computing demand at current prices and income.
A steel industry trade group estimates that the demand for steel in a particular market is given as
Qs = 2,000 - 160Ps + 8I + 140Pa,
where Qs is the demand for steel (in pounds) per year, Ps is the price of steel in cents per pound, I is income per capita in dollars, and Pa is the price of aluminum in cents per pound. Currently the price of steel is 160¢ per pound, income per capita is $20,000, and the price of aluminum is 300¢ per pound.
How much steel will be demanded at the current prices and income?