The correct answer is 18/30 which simplifies to 6/10. Hope this helps.
Area of the square: A s = s².
Area of the circle: A c = ( 1/2 s )² π = 1/4 s² · 3.14 = 0.785 s²
Area inside the square but outside the circle: s² - 0.785 s² = 0.215 s²
The ratio:
0.215 s² : s² = 0.215 : 1 = 215 : 1000 = 43 : 200 .