Looking at the picture attached, you will notice that on one side, we have a side of length 7+5=12. Next, we have a side length of 4+5+2=11. Hence, as length*width=area for a rectangle, this is the overall area of the rectangle. Next, in the picture, there are clearly two sides taken out - a 2x5 as well as a 4x5 rectangle, which are subtracted from the total area, resulting in 11*12-2*5-4*5
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