Decision variables - what are the quantities that are "directly" in our control or we are asked to figure out b. Objective function - the end goal, why do we care about making the decisions related to decision variables c. Constraints - limitations on decision variables i. Amount used of a resource <= resource available ii. Amount satisfied of a benefit >= min benefit needed iii. Any other restriction stated explicitly in the problem - look for key phrases involving restrictions such as "at least", "at most", etc iv. Implicit constraints - from the definition of decision variables such as non- negativity