In this task, you need to count the number of times the given letter appears in the given sentence.
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Question: Sentence: 'a man and a woman are walking down the street with an umbrella over their heads'. Find frequency of the letter 'w'

Answer: 4


Question: Sentence: 'a piece of meat covered in ketchup next to a hamburger on a green plate'. Find frequency of the letter 'g'

Answer: 2


Question: Sentence: 'a group of people standing outside of a train'. Find frequency of the letter 'a'

Answer:
4