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