Ключевые слова: algebra, background, black, book, calculation, calculations, calculus, close, closeup, college, drawing, education, engineering, equation, formula, geometry, homework, learning, macro, math, mathematical, mathematics, minus, monochrome, notebook, numbers, paper, plus, print, problem, school, science, scientific, scribble, sheet, sign, sinus, solution, student, study, studying, symbol, symbols, textbook, theoretical, theory, trigonometry, university, white, writing,