Ключевые слова: 20, 80, analysis, background, black, business, concept, conceptual, design, economic, education, efficiency, effort, eighty, factor, few, law, management, nobody, number, numbers, object, paper, pareto, percentage, percents, presentation, principle, productivity, proportion, result, rule, sheet, slate, sparsity, stone, table, top, twenty, view, vital, white,