I have questions, from Bazaraa's book (Linear Programming).
I have calculated point a. This is the optimal table.
Where $x_1$ is wheat, $x_2$ is corn, dan $x_3$ is soybeans.
My question is, what the meaning of point b.? Is that true if the point c. is adding a constraint $x_1\geq 120$?
I think it is safe to say that questions (b) and (c) are separate, meaning that in (c) you are limited to the original labor supply. In (b), you are given the option to expand labor beyond the original 5,000 man-days, at a rate of $3/hour and assuming a work day is eight hours. The question asks you to decide whether or not to buy more labor (not how much to buy), based on sensitivity analysis.