Complex sentence: In color theory, neutral colors are easily modified by adjacent more saturated colors and they appear to take on the hue complementary to the saturated color; e.g.: next to a bright red couch, a gray wall will appear distinctly greenish.
Split into simpler sentences: In color theory, neutral colors are colors easily modified by adjacent more saturated colors and they appear to take on the hue complementary to the saturated color. Next to a bright red couch, a gray wall will appear distinctly greenish.