Based on Angel et al. (2003). A fertilizer company is trying to determine the cheapest fertilizer mix that provides desired amounts of nutrients. The mix is made by combining the following fertilizers: SSA, SPO, GUR, TSP, KCI, FERT, and SPF. The mix can-not contain both GUR and TSP. The percentage of potassium (K), sulfur (S), calcium (Ca), sodium (Na) and phosphorus (P) in each fertilizer is listed in the file P06_88.xlsx. For example, a pound of SSA is 16% K and 26% Na. The mix must contain at least 600 pounds of K, 550 pounds of S, 750 pounds of Ca, 900 pounds of Na, and 750 pounds of P. The mix cannot contain both GUR and TSP, because if both are present in the mix, the affect of other fertilizers is nullified. The cost per pound (in cents) of each fertilizer is listed in the same file. Develop a linear integer model to find the minimum-cost fertilizer mixture that meets the stated chemical requirements.