How do you find the area of this shape?

I'm not quite sure if this helps but if it does let me know. I first started by separating the two shapes and then finding the area of the triangle (which is in red) and then after that I found the area of the rectangle (which is in Black) and after that I added both together to get the area of 198 in

520 *.04 = 20.8 which is approximately is 21.