Simplify the following text for a Grade 8 native English-speaking person.
Original: Most color wheels are based on three primary colors , three secondary colors , and the six intermediates formed by mixing a primary with a secondary , known as tertiary colors , for a total of 12 main divisions ; some add more intermediates , for 24 named colors . Other color wheels , however , are based on the four opponent colors , and may have four or eight main colors .
Simplified: The primary colors can be mixed together to make secondary colors .