In a portfolio problem, the investor has up to $50,000 to invest in stocks 1, 2, and 3, which have selling prices of $15/share, $47.25/share, and $110/share, respectively. The investor can purchase multiple shares of multiple stocks. The expected returns on investment of the three stocks are 6%, 8%, and 11%. The stockbroker suggests limiting the investments so that no more than $10,000 is invested in stock 2, and the total number of shares of stocks 2 and 3 does not exceed 350. The investor stipulates that stock 1 must not account for more than 35% of the total number of shares purchased. How should the investor make the investment to maximize the return? Formulate this problem as a linear/integer programming model (not using Excel, no need to solve it).