4x + 12x = 320
16x = 320
x = 20
We have
As we can see in order to find the shaded area of the figure, we only need to calculate the area of a square.

the shaded area is 400 mm^2
Answer:
i think 65 but if not then it is D impossible
Step-by-step explanation:
hope that helps
and that i wasn't to late