Answer:
The area of a rectangle is given by the product of its length and width. In this case, the length of the rectangle is -x + 18, and the width is x + 4. So, the area is:
Area = (length) x (width)
= (-x + 18) x (x + 4)
= -x^2 + 14x + 72
Therefore, the area of the rectangle is -x^2 + 14x + 72.