Answer:
∠b = 90°
Explanation:
If you wrote it correctly then ∠d will = 90°, right?
We have AB ║(which is parallel to) D => ∠b = ∠d = 90°
P/S: I think that you took the wrong photo, the right question should be above. I'm very please if you can take it again and I will write the right solution down below in the comment section (if u don't mind)