What is the perimeter of the triangle?

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Step-by-step explanation:

The answer is 4...

Explanation: this is a simple equation if you're trying to find X and f(x) = 12  but A(x) equals 3x your basically doing 3 times what equals 12 which in this case that would be 4 (well in any case it would be 4) I know this is confusing so hear me out (sorry)

f(x) = 12

A(x) = 3x  

3 x 4 = 12

x = 4

Like I said sorry if this makes you confused but the answer is 4 :)

brainliest? (even though I'm two weeks late)