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

[EX Q]: Sentence: 'a jet that is flying in the sky with a banner behind it'. Find frequency of the letter 'r'
[EX A]: 1

[EX Q]: Sentence: 'a person riding a camel in front of a truck'. Find frequency of the letter 't'
[EX A]: 2

[EX Q]: Sentence: 'a close up of an apple keyboard and wireless mouse'. Find frequency of the letter 'n'
[EX A]:
2