40 degrees, because ΔABC is isoceles, so angles B and C are equal.
Pls. see attachment. I found the correct format of the equation.
So just say the piece of land is in the shape of a rectangle and a triangle put together. To find the length (perimeter) add each sides up and subtract the line where the two shapes meet. To find the acreage (area) find the area of the rectangle (length*width) and add the area of the triangle (1/2*base*height)