the trick is to divide the polygon, the upper is one equilateral triangle, the middle a rectangle, the sides two right triangles and the middle another rectangle
So 2/3 of 36 is 24. So 24 that were filled and 2/3 of 40 is 80/3 which equals 26 2/3 to drain it. And then to fill the pool would be 36 hours. What's so hard...
