Do all multicellular organisms have cells that communicate?

In multicellular organisms, cells send and receive chemical messages constantly to coordinate the actions of distant organs, tissues, and cells.The ability of cells to communicate through chemical signals originated in single cells and was essential for the evolution of multicellular organisms.

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.

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