To determine the area of a triangle, we typically use the formula:
\[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} \]
However, the values you've provided (6, 18, 9, 15) seem to be possible choices for the area of the triangle.
Unfortunately, without additional context or the dimensions of the triangle (base and height), I cannot definitively select the correct area from the options given. If you can provide the necessary measurements or a diagram of the triangle, I'd be glad to help calculate the area!