Each brand of oil is resulted from blending different proportions of the four crude stocks, without any loss of material in the blending process. Additionally, each brand must meet a minimum standard for viscosity index, hence different selling prices. The relevant data concerning the three brands of oil are: Determine an optimal blending plan for a single day, assuming that daily demands are to be met precisely. In other words, the model should contain demand constraints in the form of equalities. Additionally, viscosity of a blend should be calculated as a weighted average with weights being the viscosity indices. To solve the problem, in a single Excel sheet, build an organized spreadsheet model for BO's problem and use "Simplex-LP" engine to optimize your model