The area of a rectangular section is:
[tex]\text{length}\cdot\text{width}[/tex]Knowing this, we woudl have to take the expression given and put it as the product of two factors, in order to get the lenght and with in terms of x.
In other words, we need to factor the expression as following:
[tex]\begin{gathered} 9x^2-48x+64 \\ \\ \rightarrow\frac{81x^2-48(9x)+576}{9}\rightarrow\frac{(9x-24)(9x-24)}{3\cdot3}\rightarrow(3x-8)(3x-8) \end{gathered}[/tex]This way,
Length:
[tex]3x-8[/tex]Width:
[tex]3x-8[/tex]