A bricklayers union agrees to furnish 50 bricklayers to a shoppiing mall builder. The bricklayers are classified in three categoreis according to skill; low medium and high. The total number of medium and high skilled bricklayers are to be at least 4X the number of low silled. The average number of bricks laid per hour for each skill level is low; 40 per hour, medium, 60 per hour and high, 75 per hour. The builder knows that the bricklayer crew must lay 3100 bricks per hour to remain on schedule : If the wages are $10, 15, & 18 per hour for low, medium and high skilled, respectively, how many of each type should be hired to minimize total hourly wages?

I get 31 H, 1 M, and 18 L.

We have the objective function:

min(z)=10L+15M+18H

subject to the constraints:

40L+60M+75H=3100

L+M+H=50

M+H\geq 4L

You can solve this with Excel Solver in lieu of doing it by hand.
Excel Solver works great for linear programming once you get the hang of it.

Using Solver I get 10 L, 20 M, and 20 H. I think I entered them in correctly

I forgot that H+M>= 4L. Oops!