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 working at an airport, outside of an airplane'. Find frequency of the letter 'r'

Answer: 5


Question: Sentence: 'a person riding a surfboard in the middle of a wave'. Find frequency of the letter 'o'

Answer: 3


Question: Sentence: 'a skier is skiing sideways and jumping into the air'. Find frequency of the letter 's'

Answer:
5