Answer:
5
Step-by-step explanation:
The Pythagorean Theorem states that a^2 + b^2 = c^2 for right triangles where a and b are the legs and c is the hypotenuse.
In the image, b and 12 are legs and 13 is the hypotenuse, so b^2 + 12^2 = 13^2 -> b^2 = 13^2 - 12^2 = 169 - 144 = 25 -> b = 5
I hope this helps! :)
