Answer:
The area of the window is of 840 square inches.
Step-by-step explanation:
To find the area of an trapezoid, we need to add the sum of the bases, multiply by the height, and then divide by 2.
Matematically:

In which
and
are the bases and h is the height.
In this question:

All the measures in inches, so the area is in square inches.

The area of the window is of 840 square inches.
Answer:
x = -8.
Step-by-step explanation:
Now combine the x terms. We get x - 3y = 136 and 18x + 3y = -288.
Combining these two equations eliminates the y terms, leaving us with:
19x = -152. Solving for x, we get: x = -8. This corresponds to the second answer choice.