Answer :
[tex]\begin{gathered} \text{The area of the recatangle is;} \\ x^2\text{ - 5x-36} \end{gathered}[/tex]
Here, we want to find the area of the given rectangle
Mathematically, what we have to do is to find the product of the sides
We have this as;
[tex]\begin{gathered} (x-9)(x+4)\text{ = x(x+4)-9(x+4)} \\ =x^2\text{ + 4x -9x - 36} \\ =x^2\text{ - 5x-36} \end{gathered}[/tex]