Answer:

Step-by-step explanation:
The formula of a perimeter of a rectangle:

The formula of an area of a rectangle:

l - lenght
w - width
We have l = 3w and the perimeter P = 256 in. Substitute:
<em>divide both sides by 2</em>
<em>divide both sides by 4</em>

Calculate the area of a rectangle:

The triangle ABC is the half of the rectangle. Therefore the area of a triangle ABC is:
