The two triangles are similar to each other. How long is the side labeled “?”

Answer:
12
Step-by-step explanation:
The smaller triangle seems to have dilated and formed the larger triangle. So, let's find the factor of increase.
9 / 3 = 3, so 3 is the factor of increase.
Now we need to do 4 x 3 = 12
So, ? = 12
Hope that helps!
-Sabrina