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

[EX Q]: Sentence: 'a little boy that has a toothbrush in his mouth'. Find frequency of the letter 'r'
[EX A]: 1

[EX Q]: Sentence: 'a piece of film shows two street signs crossing each other'. Find frequency of the letter 'f'
[EX A]: 2

[EX Q]: Sentence: 'a two truck towing a brinks money truck'. Find frequency of the letter 'w'
[EX A]:
2