How do I do this maths question?

Question

Answer 1

By adding the area of 4 triangles, a rectangle and the bigger rectangle I got 20

Answer 2

 The area of the rectangle in the given diagram is 10 cm^2.

 The area of the trapezium ABCD:

 (5*2) + (8/2) + (10 - 4) = 20 cm^2

Answer 3

20 cm²