We can find the area of this shape by breaking it down into similar pieces. In this case, two triangles and a rectangle.
First, the area of the rectangle. The area of a rectangle is w*h = a
w*h = a
20 * 30 = a
600 = a
Next, we can calculate the area of the triangles. They're the same measurements so we need only calculate it once, then add it twice. The measurement for the bottom is 10 + 20/2 = 20. The 20/2 came from the fact that the very bottom measurement is divided in half between the triangles. The formula for the area of a triangle is (w*h)/2 = a.
(w*h)/2 = a
(20*30)/2 = a
600/2 = a
300 = a
Now we need only to add everything up. 600+300+300 = 1200 inches^2
