You can set up an equation that equates the two areas based on the length of their perimeters. For a square if the perimeter is x then one side is length x/4, and the area is (x/4)^2. For a circle if the circumference is y then the radius is y/(2 pi) and the area is y^2/(4 pi). Set these two areas equal, and add in the condition that x + y = 360, and solve for x and y.