To find the scale factor between triangle A and triangle B, you can compare their corresponding side lengths.
Let's compare the corresponding sides of triangle A and triangle B:
A:
Legs: 5 and 12
B:
Legs: 15 and 36
To go from triangle A to triangle B, you can see that the corresponding sides of triangle B are 3 times longer than the sides of triangle A.
So, the scale factor is 3.