I never understand these

This shape can be broke down into 2 rectangles and 2 triangles.

Let’s first find the area of the bigger rectangle:

To find area you just multiply l•w, or length•width.

For the big rectangle, the length is 20, and the width is 5. When these are multiplied you get 100.

So, the area of that first shape is 100. Now we have to find the others, using the same process!

The small rectangle has a length width of 4, but the length is not there.

In order to find the length, you have to use the bigger rectangles length, but subtract the left and right sides (the 5’s).

So it looks like this;
20-5-5 = 10!

The length is 10 and the width is 4. Now just multiply!

10•4 = 40

Now for the last shapes. Typically with a triangle you would divide it by two, but since you already have to triangles, you can combine them to make like a square shape.

So, once again, you do l•w:
5•4=20
(no further steps since you have two triangles already)

Now that we have the area of every individual shape, you just add them all!

100+40+20= 160

Your answer is 160 (but make sure to add in your unit, and when finding area you have to add the little 2)

So it’s 160in.^2