Alternative Solution:

Let u be the side of the square.

0.2m = 20 cm,  0.1m = 10cm

20(2u+10) + 10(3u) = 3000

40u+200+30u = 3000

70u=2800

u=40

Therefore area of rectangle = 2u x 3u = 2(40) x 3(40) = 80 x 120 = 9600 cm²

Let x be one side of the a square in cm.

(3x + 20) (2x + 10) – 3000 = 3x * 2x
6x² + 40x + 30x + 200 – 3000 = 6x² 
70x = 2800
x = 40

So area of shaded rectangle = 6x² = 6 (40)² = 9600 cm² #