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

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

[EX Q]: Sentence: 'a giraffe sticking it's tongue out near a window'. Find frequency of the letter 'a'
[EX A]: 4

[EX Q]: Sentence: 'a man standing on a skateboard ramp and another person standing on the lower ground next to a skateboard'. Find frequency of the letter 'b'
[EX A]:
2