## Elementary Algebra

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: $A_{parr.} = 10(10) = 100 \\ A_{rect.} = 10(20) = 200$