help

Well Im going to give ya my method:

The diagonal of the square is equal to the diameter of the circle around it.

The Diameter of that circle is equal to the side length of the square around it.

So you just keep calculating. Quite a tedious problem, once you know the method.

Diagonal of red square =   5√2  =  side of second largest square

5√2 * √2  =  5 * 2   = 10    =  side of largest square

So  the area of the largest square  =   10^2  =   100 units^2