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

[Q]: Sentence: 'silhouette of person playing frisbee with moutain and sunset'. Find frequency of the letter 'i'
[A]: 5

[Q]: Sentence: 'a red stop sign with street signs above it'. Find frequency of the letter 't'
[A]: 5

[Q]: Sentence: 'a photo of a ferry on the water with mountains in the background'. Find frequency of the letter 'f'
[A]:
2