What is peristalsis? how does it work in the esophagus?

Peristalsis is part of the food digestion process. it's a helpful function we have

Explanation:

answer; /// i believe that the correct answer is; ///a combination of the birth and death

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.

: -)