Not sure what I'm doing wrong, please help explain. Thank you!

about 50 degrees

Step-by-step explanation:

To find the angle you would first subtract 180 - 90 (Since a triangle always equals 180) and that would be 90 and then divide by 2 to equal 45. I believe they wanted to round to nearest tenth so then the answer would change to 50. (Tell me if this is wrong; its been a while since I have done this)

I hope this helps :)