Two parrots have different parents. One parrot has red chest feathers, and the other parrot has yellow chest feathers. Why do the parrots have different feather colors on their chest?

Hereditary traits.

Explanation:

Since these two parrots (with two different parents), one with yellow feathers and the other one red, it would make sense that they inherited their traits from their parents.

Just as humans have different colors of hair. Parrots can have different chest colors. Both of these come from hereditary genes.

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

i think it is dna, i'm not totally sure but i think it might be.