First, find the area of the whole figure and then subtract the area of the cut out triangle.
Area of whole figure:
It’s just a rectangle, so 18 * 8 = 144 units squared
Area of the triangle:
We know the base is 8, but we need to find the height. The height of an equilateral triangle is always a (the side)/2 * sqrt(3). So, the height is 4 * sqrt(3).
The area of the the triangle is (8 * 4sqrt(3))/2 = 16 * sqrt(3).
So, we do 144 - 16 * sqrt(3) is about 116.3 units squared, or choice (B).
