We have to find the shaded area.
This can be calculated as the difference between the big rectangle and the small rectangle.
We then can write:
[tex]\begin{gathered} A=A_b-A_s \\ A=(x+8)(x+6)-3x(x+3) \\ A=x^2+8x+6x+48-3x^2-9x \\ A=-2x^2+5x+48 \end{gathered}[/tex]
Answer: the shaded area is equal to A = -2x^2+5x+48
