Positive colors R,G,B, where R+G=Y, R+B=M, G+B=C, and R+G+B=W; negative colors C=W-R, M=W-G, Y=W-B, where M+Y=R, Y+C=G, and M+C=B; and R+C=W, G+M=W, and B+Y=W; and M+Y+C=B. Here R=red, G=green, B=blue, Y=yellow, M=magenta, C=cyan, W=white and B=black (absence of color).
The color of the actual slide is much more vivid than the representation in the photograph above, due to limitations of digital displays.