The color wheel does show the relationship of RGB and CMY colors. Yellow is opposite Blue, and between Red and Green. Magenta is opposite Green, and between Red and Blue. Hue and Saturation tools use this color wheel too, although few show it clearly. Hue is the movement around the circle, Red is 0 degrees, Green is 120 degrees, and Blue at 240, returning to red at 360 degrees.
Saturation is a move across the radius of the circle.
The center is gray. But the Photoshop Color Balance range also does not have sufficient range for this particular image, the required change is too extreme. Notice the relationship in the colors is the same here, that Cyan is the inverse of Red, etc. Anyway, that scan from ScanWizard above is vastly better, but it is still light pink all over, particularly noticeable in the sky. The spots are green.