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

[EX Q]: Sentence: 'a yellow fire hydrant in the forefront of a roadway'. Find frequency of the letter 'r'
[EX A]: 5

[EX Q]: Sentence: 'a group of cars and house on truck passing in a street'. Find frequency of the letter 'i'
[EX A]: 2

[EX Q]: Sentence: 'a grizzly bear standing on concrete in an iron barred cage'. Find frequency of the letter 'n'
[EX A]:
7