There are 1 questions in this calculation: for each question, the 1 derivative of l is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ 25{l}^{\frac{1}{3}}{k}^{(\frac{2}{3})} + c(300 - 20l - 20k)\ with\ respect\ to\ l：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = 25k^{\frac{2}{3}}l^{\frac{1}{3}} - 20cl + 300c - 20kc\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( 25k^{\frac{2}{3}}l^{\frac{1}{3}} - 20cl + 300c - 20kc\right)}{dl}\\=&\frac{25k^{\frac{2}{3}}*\frac{1}{3}}{l^{\frac{2}{3}}} - 20c + 0 + 0\\=&\frac{25k^{\frac{2}{3}}}{3l^{\frac{2}{3}}} - 20c\\ \end{split}\end{equation} \]

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