Let us find the area of some parts and then sum them.
First part: 3 Rectangles of length 20 mm and width 10 mm
A= 3*l*w (A:area of 2 rectangles, l:side length)
A= 2*(10)^2 mm^2 (Replacing)
A=2*100 mm^2 ( Raising 10 to the power of 2)
A= 200 mm^2
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