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 on a sidewalk jumping with an umbrella'. Find frequency of the letter 'a'

Answer: 5


Question: Sentence: 'the large modern train is on the train track'. Find frequency of the letter 'm'

Answer: 1


Question: Sentence: 'the animal runs on the green grass in the sun'. Find frequency of the letter 'g'

Answer:
2