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

[EX Q]: Sentence: 'a girl laying on a bed posing for a picture'. Find frequency of the letter 'i'
[EX A]: 4

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

[EX Q]: Sentence: 'dog on a leash sitting in a bus surrounded by people'. Find frequency of the letter 'e'
[EX A]:
4