Red, green, and blue contribute differently to the color of white. The fundamental reason is that the retina of the human eye has different perceptions of light of different wavelengths.
After a large number of experimental tests, the following approximate ratios were obtained: the simple red, green, and blue brightness ratio is: 3:6:1, and the precise red, green, and blue brightness ratio is: 3.0:5.9:1.1.