Answer:
3/5
Explanation:
I just looked up how to do this since I've never done it before, so if I'm wrong I'm sorry, but from what I found all you have to do is put the opposite(o) over the hypotenuse(h) o/h which would be 9/15 and simplified it would be 3/5, and again if I'm wrong I'm sorry.
I hope this helps, and have a great day!