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

[Q]: Sentence: 'a man with a large grey and black beard and glasses and a tie'. Find frequency of the letter 'e'
[A]: 5


[Q]: Sentence: 'a man with a skateboard that is in the street'. Find frequency of the letter 'o'
[A]: 1


[Q]: Sentence: 'there are two zebras standing next to each other'. Find frequency of the letter 'a'
[A]:
4