Colored pencil on paper, 6.5" x 10"
The primary colors are called that because they are the three colors which cannot be mixed from any other colors, and from which any other colors can be mixed.
The appearance of the red and yellow and blue colors will vary in different pigments, paints or other art supplies, but if you have any red, any yellow and any blue, you will be able to mix other colors from them.
In this drawing, the red I chose appears to be more of a red-orange than a true spectrum red, and the blue is not as saturated as a true spectrum blue, but the yellow is very close to a true spectrum yellow. Remember, too, that computer monitors are not all calibrated equally and that color-matching is a pretty imprecise science. What you see is what you get!