Read this: In modern color theory, also known as the RGB color model, red, green and blue are additive primary colors. Red, green and blue light combined together makes white light, and these three colors, combined in different mixtures, can produce nearly any other color. This is the principle that is used to make all of the colors on your computer screen and your television. For example, purple on a computer screen is made by a similar formula to used by Cennino Cennini in the Renaissance to make violet, but using additive colors and light instead of pigment: it is created by combining red and blue light at equal intensity on a black screen. Violet is made on a computer screen in a similar way, but with a greater amount of blue light and less red light.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What colors are used to create purple on a computer screen?
red and blue