Final Answer:
The value of (x) that makes the vertical parts of the letter N parallel is (1).
Step-by-step explanation:
In the context of the letter N, for its vertical parts to be parallel, the angles formed by the intersecting lines must be equal.
In this case, the expression (3x + 9) represents one of the angles.
To find the value of (x) for parallel vertical lines, set the expression equal to another vertical line expression or a constant.
So, (3x + 9 = k), where (k) is a constant representing the other vertical line. By solving for (x), we get (x = frac{k - 9}{3}).
For the vertical parts to be parallel, (k - 9) must be a multiple of 3, making (x) an integer.
Setting (k - 9) equal to 0 gives us (k = 9), so the value of (x) that makes the vertical parts of the letter N parallel is (1).
In summary, the correct value of (x) is (1) to ensure the vertical parts of the letter N are parallel.