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: 'group of snowboarders on a snowy trail overlooking a mountain'. Find frequency of the letter 'r'
[EX A]: 5

[EX Q]: Sentence: 'a little kitty on the bed using a laptop'. Find frequency of the letter 'i'
[EX A]:
3