Answer:
C
Explanation:
Let's call the middle M. If we take triangle PMQ we see that is has a 90 degrees angle. Also both of the other corners are equal so 180=90-2x. x=45 degrees. In a triangle with two 45 degrees angles and a 90 degrees angle the following applies: Both straigth sides are 1:square root of 2 to the oblique side. That means that if say PM=4 that PQ=4sqrt2. Now we'll that to determine PM. PQ=5x so PM=5xsqrt2. The area of parallelogram PQRS then equals to 5xsqrt2×5xsqrt2=25x^2×2=50x^2. So that is C.