help me find N and get this right

Answer:
N = 18
Step-by-step explanation:
The triangles are similar, thus the ratios of corresponding sides are equal, that is
[tex]\frac{5}{15}[/tex] = [tex]\frac{6}{N}[/tex] ( cross- multiply )
5N = 90 ( divide both sides by 5 )
N = 18