Talk:Test Tube/@comment-35822353-20180723215044/@comment-36116492-20181109162154

Red and green are complementary colours (on the opposite side of the colour wheel) which means they are opposites.

A good way to remember is to think about what colour you'll get when mixing them together. Usually, you won't have an answer for complementary colours or will come up with gray or brown. If you mix cyan and red together, it's similar to mixing red and blue (which would make purple).

When you invert the colours on gadgets though, red turns into cyan. I honestly don't know why, but I do know that green is the opposite of red.

Hope this helps :D