Use algebra tiles to find the difference. let one yellow tile equal +1 and one red tile equal –1. 11 – 12 a. -23 b. -1 c. 23 d. -3

So you have 11 yellow tiles and 12 red tiles. Each yellow tile can be canceled out by a red tile. If you take 11 of each tile, you'll end up with one red tile, or -1. B is your answer

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the branch of biology that deals with the normal functions of living organisms and their parts.

the way in which a living organism or bodily part functions.