With what?
Red is a primary colour and although it is one of the colours used to create secondary and tertiary colours and shades it is not possible to mix other colours to achieve a true red.
Red and orange
you get purple
red and brown
red and yellow
you can mix the colours red and blue
to get a tertiary colour you have to mix 2 primary colours. primary colours are red, blue and yellow.
dark green
Brown
Red is a primary colour. It is one of the building blocks of colour. This means you can mix other primary colours (blue & yellow) to it to achieve secondary and tertiary colours, but you can not mix other colours to achieve red.
red is a primary colour, so you cannot mix colours to get red.
You can mix primary colors (red, blue, yellow) to create secondary colors: Red + blue = purple Blue + yellow = green Yellow + red = orange You can also mix primary and secondary colors to create tertiary colors like: Red + orange = red-orange Blue + green = blue-green Yellow + green = yellow-green