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

[Q]: Sentence: 'an image of a street sign with a corner restaurant'. Find frequency of the letter 'u'
[A]: 1


[Q]: Sentence: 'a photo of a couple of people at a convention'. Find frequency of the letter 'v'
[A]: 1


[Q]: Sentence: 'a duel colored bus with a large mustache on its front'. Find frequency of the letter 't'
[A]:
4