Respuesta :

Answer: [tex]12x+4[/tex]

Step-by-step explanation:

We need to add all the sides of the triangle together in order to find the perimeter. The equation to find the perimeter of a triangle is:

[tex]perimeter = side 1 + side 2 + side 3[/tex]

Since the question gives us the sides, let's plug it into the equation:

[tex]perimeter = (3x+7) + (4x-9) + (5x+6)[/tex]

To simplify the equation, first, let's add the x variables together  (remember that we can't add two different variables together, so we can't just add all the numbers together! we have to add the two different variables separately):

[tex]3x + 4x + 5x = 12x[/tex]

Do the same to the other variable:

[tex]7 + (-9) + 6 = 4[/tex]

Put the two variables together:

[tex]12x+4[/tex]