First, I would work from let to right, but that doesn’t matter.
Ok so, to find the area of the very left rectangle, 20 x 24 = 480
Then, to find the area of the middle rectangle, 24 x (24 + 16) = 960
Then, to find the area of the last rectangle, 28 x 24 = 672
Last, add them all together: 2112