To find the third side length, we can use the fact that the sum of the lengths of any two sides of a triangle is greater than the length of the third side. So we can write: (z + 13) + (2z + 6) > third side Simplifying the left side, we get: 3z + 19 > third side Now we also know that the perimeter of the triangle is the sum of the lengths of all three sides, so we can write: (z + 13) + (2z + 6) + third side = 8z + 11 Simplifying this equation, we get: 3z + 19 + third side = 8z + 11 Subtracting 3z + 19 from both sides, we get: third side = 5z - 8 Therefore, the