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

[Q]: Sentence: 'a group of people standing on grass with a train in the background'. Find frequency of the letter 'n'
[A]: 6


[Q]: Sentence: 'bananas are being dried in a tropical setting'. Find frequency of the letter 'i'
[A]: 5


[Q]: Sentence: 'a man is pulling a couple of bags down the street'. Find frequency of the letter 'l'
[A]:
3