In this task, you need to count the number of times the given letter appears in the given sentence.

Example input: Sentence: 'a large group of bananas proped up on several bicycles'. Find frequency of the letter 'e'
Example output: 5
Example explanation: The letter 'e' appears 5 times in the sentence.
Q: Sentence: 'a couple of men standing by a sign with frisbees'. Find frequency of the letter 'b'
A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
2