Okay so you split up each one into different shapes, which is a good start.
Next, you can see that the two smaller rectangles are the same size: 3 cm by 1.5 cm. To find the area of those, multiply 3 by 1.5 to get 4.5. Now multiply that by two since both small rectangles are the same.
Next, to find the area of the bigger rectangle, multiply 6 by 7.5 to get 45 cm.
Finally, add 9 and 45 together to get a total area of 56 cm