Cell Theory states: I. All living cells must have a cell wall. II. All living cells require glucose for survival. III. The basic unit of life is a cell membrane.

the answer is lll.

Explanation:

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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