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 street at night with trees and streetlights on'. Find frequency of the letter 't'

Answer: 9


Question: Sentence: 'a group of tennis players on a tennis court'. Find frequency of the letter 'o'

Answer: 4


Question: Sentence: 'a big truck going in one direction and a smaller truck going in the opposite direction'. Find frequency of the letter 'a'

Answer:
4