Answer:
A
Explanation:
The larger and smaller right angled triangles in the diagram are similar with linear scale factor 2. The area of the smaller white triangle is 1/2(3)(4) = 6.
The area scale factor = 2² = 4, so the area of the larger triangle is 4(6) = 24.
Hence the shaded area = 24 - 6 = 18.