Hi Piwollo,
What he means is extend the vertical line to where it divides the figure into two separate rectangles.
The vertical rectangle will be 1.0m by 0.4m.
The horizontal rectanglw will be 1.0m by 0.4m, as well.
Use Area = length times width to find the area of each rectangle.
Then add them together to obtain the area of your unique figure.
A different, yet not easier way than the others have posted (but maybe to make you see it from a 'different' angle as well) would be to make a square of the whole thing. The area of a square is where a and b is the sides. In this case you would make 2 squares. One that covers it all: and one which contains the area you arent interested in IE Now subtract the square you arent interested in, away from the large one.
Happy calcing.