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

[Q]: Sentence: 'a railroad train pulling up to the train platform'. Find frequency of the letter 'o'
[A]: 3


[Q]: Sentence: 'a baseball themed birthday cake is on a serving tray'. Find frequency of the letter 'g'
[A]: 1


[Q]: Sentence: 'a man wearing headphones looking at the camera'. Find frequency of the letter 'l'
[A]:
1