Additive (light) primary colors are red, green, blue (matching our color perception). Mixing them gives white (in the correct proportions, matching our color sensitivity).
Subtractive (pigment) primary colors
WERE (when I went to school) red, yellow, blue (under the historical
RYB color model). But in real life you also need black pigment (not considered a color) to get anything darker than a muddy brown.
EDIT: I just learned (thanks pdurrant) that a new (since I went to school) color model is in use: CMY, with new primary colors Cyan, Magenta, and Yellow (which actually makes much more sensse considering that it avoids that "muddy brown" problem with the old subtractive color model).
Inkjet printers typically use CMYK colors (cyan, magenta, yellow, plus black to give richer blacks).
Now color eink is just magic, until I learn how the technogy really works, and magic disturbs me. Though I was a licensed magician as a child -- my cousin was a professional magician and he taught me tricks and registered me for the license. Not sure what honors that bestowed. My amateur radio and motorcyle and SCUBA and firearm safety (and more) are more useful than being a certified magician, I think...
But I love learning the secrets underlying magic tricks, converting mystery to knowlege and magic to science.
Yeah, that "technical trickery' disturbs me, because known unknowns cause an itch that is only relieved by learning their secrets...