Answer:
54 squared units.
Explanation:
The area of the triangle in the image attached can be calculated with the formula to areas of triangles:

Where b is the base and h is the height. It's important to consider that the height is the segment that goes from a vertex to the opposite side, forming a right angle, like this case. This definition is really important because that's the clue to identify the height.
So, applying the formula to this problem, we have b = 18 and h = 6.

Therefore, the area of the given triangle is 54 squared units.