Notice that the area is equivalent to the area of the complete rectangle minus the area of the 3km x 4km rectangle.
[tex]A=TA-AS\text{.}[/tex]
Now, the area of a rectangle is given by the following formula:
[tex]A=\text{width}\cdot\text{lenght.}[/tex]
Therefore:
[tex]A=9km\cdot16km-3km\cdot4km\text{.}[/tex]
Simplifying the above result, we get:
[tex]A=(144-12)km^2=132km^2.[/tex]
Answer:
[tex]132km^2.[/tex]
