Answer:
The area of the trapezoid is 165.06mi.
Explanation:
We can find the area of a trapezoid by the following formula:

is the area of the trapezoid (in our case, it is what we want to find)
is the biggest base (in our case, the biggest base is 18.5 mi)
is the smallest base (in our case, the smallest base is 6.7 mi)
is the height (in our case, the base height is 13.1 mi)
Note: Base are the parallel sides of the trapezium.
Now, let's change the values in the previous formula:

Therefore, the area of this trapezoid is 165.06 mi.
I hope I've helped.
Happy studying! =D