Answer:
20 square feet
Explanation:
area of a triangle = (1/2) base x height
The "base" for this one gigantic triangle is the 'top' of the diagram - - - - it's the entire 3+7 = 10 side. (We can calculate the area of the whole thing at once. We don't have to do the left and the right halves separately!!!)
The height is 4.
So area = (1/2) base x height
= (1/2) * 10 * 4
= 20 square feet