Primary colors - light vs. paint?

The asker is correct. The asker is describing the properties of both subtractive and additive primarys.

Additive is generated by emitted light, not reflected light. Combining of the 3 primaries of red green and blue at equal saturation will result in white light

Subtractive primarys are the result of reflected light generally from pigments in paint. Combinging of the 3 primaries Magenta (red), Cyan (blue) and yeallow in equal amounts will result in a greenish muddy color.

Im not sure the full reason, but the absorption of light by a material substances does follow different rules from the perception of emitted light by the eye

The 7 colors mentioned in the answer are complimentary colors not primary colors.

There's two types of primary colors, additive and subtractive colors. The primary colors you learn about in grade school are subtractive, and are technically magenta, cyan, and yellow that when mixed together form black or the absence of color. However white is formed by the mixing of the additive primary colors red, green, and blue. The formation of white is best demonstrated using light and is a topic of most basic physics classes.

Um, yeah...they're all the same. The primary colors (of light and paint, as well as crayons) are red, blue and yellow. Green is always a secondary color, as it is created by blending two primary colors, which are blue and yellow.

The light has 7 basic colors in the visible spectrum, not 3.

Primary colors are red, blue, and yellow. It doesn't matter how light they are.