With a side of length 12, we have an area of 144. The circle's radius is 3, so their area is 9π, per circle. All four circles have a total combined area of 36π - green. The area that is left of the square after the circles are painted green is 144-36π - White
So, the ratio of Green:White is (36π) : (144-36π), which simplifies to π:(4-π), B