There are 1 questions in this calculation: for each question, the 1 derivative of x is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ 20 - \frac{4x}{1}\ with\ respect\ to\ x：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = - 4x + 20\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( - 4x + 20\right)}{dx}\\=& - 4 + 0\\=& - 4\\ \end{split}\end{equation} \]

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