Hello!
To find the perimeter of any rectangle, use the formula P = 2l + 2w.
In this formula, l is the length and w is the width. Given that the width is 2x + 9 and the length is x + 4, we can find the perimeter.
P = 2(x + 4) + 2(2x + 9)
P = 2x + 8 + 4x + 18
P = 6x + 26
Therefore, the perimeter of the rectangle is 6x + 26.