What would happen if a dominant trait joined with the recessive trait? What is the end result? (Based off Gregor Mendel)

A dominant allele hides a recessive allele and determines the organism's appearance

When a dominant trait joins with the recessive trait, only the dominant trait will show when determining the organism's characteristics.

Explanation:

The dominant trait is "dominant" so it will mask the recessive trait. For example, brown eyes is a dominant trait for the color of someone's eye. Blue eyes is a recessive trait. If someone were to have both genes when they were born, they would have brown eyes because it masks the genes for blue eyes.