Good work, in arriving at one of the correct solutions, Briana..
I would just like to clarify what others mean by there being two solutions: there are two triangles, each sharing vertices at $(0,3)$ and $(4,0)$ (and hence they share a side). But there are two values for the unknown $x$ in the vertex $(x, 5)$ that yield a triangle with area $8: x = \frac {8}{3} = (2.66$ repeating), and $x = -8.$
In other words, the area of the triangle with third vertex $( \frac {8}{3}, 5)$ and the area of triangle with third vertex $(-8, 5)$ both equal $8$.
