Ключевые слова: 20, 80, 8020, abstract, background, blackboard, business, businessman, compare, concept, drawing, economy, education, effect, eighty, eightytwenty, encourage, finance, financial, gincentive, idea, law, letter, majority, management, marker, motivation, note, paper, percent, percentage, plan, principle, profit, rule, sign, symbol, text, theory, think, twenty, word, write,