<PRE><B>Question 109586</B>
Remember the perimeter is the sum of all sides of a triangle. So if the sides are 3x + 7, 4x - 9, and 5x + 6, simply add them all up to get


{{{Perimeter=(3x + 7)+(4x - 9)+(5x + 6)}}}


{{{Perimeter=(3x+4x+5x)+(7-9+6)}}} Group like terms


{{{Perimeter=12x+4}}} Combine like terms



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