#### Answer

The answer is below.

#### Work Step by Step

We are told:
$A_{parr.} = 2 A_{rect.}$
Using the equation for the area of each and calling the length of the side that has the same measure for each s, we obtain:
$ s^2 = 20s \\ s=20 $
Thus:
$A_{parr.} = 10(10) = 100 \\ A_{rect.} = 10(20) = 200$