Since the triangles are similar, they will have proportional sides. With this knowledge, we can make the proportion [tex] \frac{8}{10} =\frac{x}{5} [/tex] to solve for x.
Firstly, cross multiply: [tex] 40=10x [/tex]
Next, divide by 10 on both sides, and your answer will be 4 = x, or the first option.
