There are 1 questions in this calculation: for each question, the 1 derivative of t is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ (x - 4)(5x + 15)\ with\ respect\ to\ t：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = 5x^{2} - 5x - 60\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( 5x^{2} - 5x - 60\right)}{dt}\\=&0 + 0 + 0\\=&0\\ \end{split}\end{equation} \]

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