Answer:

Explanation:
The picture of the question in the attached figure
we know that
The area of a trapezoid is equal to
![A=(1)/(2)[b_1+b_2]h](https://img.qammunity.org/2021/formulas/mathematics/middle-school/eoftq0ulsfrc7kps8r829y2vcwt9jyx5wl.png)
where
b_1 and b_2 are the length of the parallel bases
h is the height (perpendicular distance between the parallel bases)
we have

substitute
![A=(1)/(2)[210+480]320=110,400\ mi^2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/wtfj4yviz4xownobl640gixyj3jymdf2ri.png)