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

[EX Q]: Sentence: 'a double decker transit bus parks by a blue on the side of the street in front of a brick building in the city'. Find frequency of the letter 't'
[EX A]: 9

[EX Q]: Sentence: 'a group of people walking down a rain soaked street with umbrellas'. Find frequency of the letter 'w'
[EX A]: 3

[EX Q]: Sentence: 'a giraffe standing on a lush green field of grass'. Find frequency of the letter 'f'
[EX A]:
4