A total of 12 dogs are in the final round of a competition for ugliest dog. How many ways can 1st place through 3rd place prizes be awarded? Enter your answer in the box.

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  divide by x

Step-by-step explanation:

To answer your question, you can get from A to B by dividing by x:

However, this is only a valid operation if x ≠ 0. In this equation, x = 0, so that division is not valid.

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A better approach to the solution is to put the equation in standard form:

  f(x) = 0

You can get there by subtracting 3x from both sides.

  5x -3x = 3x -3x

  2x = 0

Now, you can legitimately divide by 2 to find ...

  x = 0 . . . . . . . . the reason why dividing by x is not allowed