Question

The area of the shape

Answer 1

Yes, to find the area of a rectangle you do base times height, in this case 20 x 10. 
But, if you look at the shape, there is a little corner cut off of the shape. 
That means that you have to add some steps to solving it. 

You can see that there are two sides shorter. 
One is 16 instead of 20, and the other is 8 instead of 10. 
That means that the dimensions of the triangular cutout is 4 x 2, since one side is 4 m shorter and the other 2 m shorter. 

The cut-off piece is a triangle, so the area of the triangle won't be 4 x 2 it will be half of that. 
4 x 2 = 8, and 1/2 of 8 is 4. 

That means 4m has been cut off of the rectangle. 
Initially, the rectangle was 200 m². 
Subtract 4 m², and the actual area of the shape is... 
Dun dun dun...
196 m²!
 
Hope this helps!