Once again same method as I've explained before. However, this one tricked me a little bit and still is because of the appearance of the smaller triangle. However, If I don't focus on that I believe this answer is correct. This is because in order to find the missing side we need to find the factor of which the triangle was expanded. So we must divide a given side of the bigger triangle by the same similar side of the little triangle, like 15/5. Then we must divide n by its similar side which the appearance made me think 13 which is not an option so I believe it is 12 and it was just trying to throw me off. So n/12. Therefore that is why I believe B is correct.
