Question 82708
The perimeter is the sum of all sides, in other words the perimeter (p) equals


{{{p=side1+side2+side3}}}

where side1=3x+7, side2=4x-9, and side3=5x-6


so it becomes


{{{p=(3x+7)+(4x-9)+(5x-6)}}} plug in the given information


{{{p=(3x+4x+5x)+(7-9-6)}}} Group like terms


{{{p=(12x)+(-8)}}} Combine like terms


So the perimeter is 


{{{p=12x-8}}}