A triangle has vertices at (0,0), (6,0), and (0,8). What is its area?

The vertices $(0,0)$, $(6,0)$, and $(0,8)$ form a right triangle with legs along the axes: the horizontal leg has length $6$ and the vertical leg has length $8$. The area is $\frac{1}{2}(6)(8)=24$, choice J. Choice G ($48$) is the product of the legs with the factor of $\frac{1}{2}$ left out, which is the area of the rectangle. Choice F ($14$) is the sum of the legs. Choice H ($28$) is twice that sum. Triangles have half the area of the rectangle that contains them.