question: \overrightarrow B D bisects \angle A B F. If m \angle F B C = 2 x + 25 and m \angle A B F = 10 x - 1, find m \angle D B F.
  Choices:
  A:25.5
  B:50
  C:54
  D:64.5
query_wo: Please directly answer the question and provide the correct option letter, e.g., A, B, C, D.
  Question: \overrightarrow B D bisects \angle A B F. If m \angle F B C = 2 x + 25 and m \angle A B F = 10 x - 1, find m \angle D B F.
  Choices:
  A:25.5
  B:50
  C:54
  D:64.5
query_cot: Please first conduct reasoning, and then answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
  Question: \overrightarrow B D bisects \angle A B F. If m \angle F B C = 2 x + 25 and m \angle A B F = 10 x - 1, find m \angle D B F.
  Choices:
  A:25.5
  B:50
  C:54
  D:64.5
question_for_eval: \overrightarrow B D bisects \angle A B F. If m \angle F B C = 2 x + 25 and m \angle A B F = 10 x - 1, find m \angle D B F.
  Choices:
  A:25.5
  B:50
  C:54
  D:64.5