If a cell divides by mitosis so that one cell eventually becomes part of the brain and the other cell becomes part of a salivary gland, the cells have

 The cells  have  differentiated.

Explanation:

The process by which a cell changes from one type to another is called cellular differentiation. When this happens, the cell changes to a more specialized type. So this creates differentiated daughter cells which are important in a multicellular organism because they are able to perform different and specialised functions in an organism.

as many times as you want

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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