Set up the initial tableau, do not solve.
A bricklayers' union agrees to furnish at least 50 brick layers to a shopping mall builder. The bricklayers are classified in three categories according to skill: low, medium, and high. The union requires that the total number of medium- and high skilled bricklayers be at least four times the number of low skilled. The average number of bricks laid per hour for each skill level is: low, 40 per hour; medium, 60 per hour; high, 75 per hour. The builder knows that the bricklayer crew must lay at least 3100 bricks per hour to stay on schedule. If the wages per hour are $10, $15, and $18 for low, medium, and high skilled, respectively, how many of each type should be hired to minimize total hourly wages?