Understanding Color Mixing
When you mix the color orange with red, you are essentially combining two warm colors together. Since orange is already made by mixing red and yellow, adding more red will make the orange color richer and more intense. The resulting hue is a deeper, more vibrant shade of orange, leaning towards a reddish-orange depending on the amount of red color added.
Subsequently, mixing this reddish-orange with blue, which is a primary color, will give you a more complex color. Blue being on the opposite side of the color wheel to orange and red will tend to neutralize the warmth of the orange-red mixture to some extent. Depending on the proportions of the mix, you could end up with various shades of brown or a muted purple. This happens because blue mixed with orange (which itself is a mix of red and yellow) results in a subtractive color mixing process, which can result in different shades of brown, grey, or even muddy colors, since blue combined with yellow gives green, and when you mix red, green, and blue (all three primary colors) you generally get a color close to grey or brown.