The area of the shaded region is the area of the large rectangle minus the smaller rectangle. The area of a rectangle is l*w, so the area of the large rectangle is (x+7)(2x+3), which equals 2x^2 + 17x + 21. The area of the smaller triangle is equal to x(x+2) which equals x^2 + 2x.
The shaded region is (2x^2 + 17x + 21) - (x^2 + 2x), which equals x^2 + 15x + 21
So, the final answer is x^2 + 15x + 21 units squared