If the triangles in the figure are similar what is the length of side b?

Answer:
A 36
Step-by-step explanation:
We can determine the scale factor
From triangle ABC BC =9
DEF EF = 90
We multiply by 10
The scale factor is 10
AC ( 10) = DF
We know DF = 360
b * 10 = 360
Divide each side by 10
10b/10 = 360/10
b = 36