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 cannot 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 200 pounds of K, 220 pounds of S, 240 pounds of Ca, 260 pounds of Na, and 280 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 also listed in the file P06_88.xlsx. Develop a linear integer model to find the minimum cost fertilizer mixture that meets the stated chemical requirements.