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

[Q]: Sentence: 'a little boy sitting on a bed in a bedroom'. Find frequency of the letter 'e'
[A]: 3

[Q]: Sentence: 'a yellow and green train on a train track in a wooded area'. Find frequency of the letter 'o'
[A]: 4

[Q]: Sentence: 'the two men are play a table tennis computer game'. Find frequency of the letter 'e'
[A]:
7