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

[EX Q]: Sentence: 'there is a person standing on a blue towel'. Find frequency of the letter 'n'
[EX A]: 4

[EX Q]: Sentence: 'a bunch of broken down trains sit in a yard'. Find frequency of the letter 'n'
[EX A]: 5

[EX Q]: Sentence: 'two hotdogs and two sodas set out for lunch'. Find frequency of the letter 's'
[EX A]:
4