The area of the parallelogram is base*height = 20*16=320. Add that to the area of the triangle which is base*height*1/2 = 8*20*1/2 = 80
320 + 80 = 400
Note = We know the base of the triangle is 20 because it is a side of a parallelogram, so its measure is the same as the one of its opposite side = 20.
