The two prism below are similar what is the value of x

Answer:
C
Step-by-step explanation:
Since the figures are similar then the ratio of corresponding sides are equal, that is
[tex]\frac{3}{15}[/tex] = [tex]\frac{1}{x}[/tex] ( cross- multiply )
3x = 15 ( divide both sides by 3 )
x = 5 → C