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 person that is looking out his window'. Find frequency of the letter 'n'

Answer: 3


Question: Sentence: 'small airplane in the process of taking off'. Find frequency of the letter 'e'

Answer: 3


Question: Sentence: 'the bathroom sink has very tall wooden cabinets'. Find frequency of the letter 'e'

Answer:
4