There are 1 questions in this calculation: for each question, the 1 derivative of p is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ 9 - 4p\ with\ respect\ to\ p：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = - 4p + 9\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( - 4p + 9\right)}{dp}\\=& - 4 + 0\\=& - 4\\ \end{split}\end{equation} \]

Your problem has not been solved here? Please take a look at the  hot problems ！