In this task, you need to count the number of times the given letter appears in the given sentence.

[EX Q]: Sentence: 'a group of giraffes walk together by a hill'. Find frequency of the letter 'b'
[EX A]: 1

[EX Q]: Sentence: 'apples, pears, and oranges are piled up for sale'. Find frequency of the letter 'a'
[EX A]: 6

[EX Q]: Sentence: 'a big bowl of different kinds of fruit inside'. Find frequency of the letter 'b'
[EX A]:
2