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

[EX Q]: Sentence: 'this is an image of a woman playing tennis'. Find frequency of the letter 'f'
[EX A]: 1

[EX Q]: Sentence: 'a woman in a tank top reaches out for a frisbee'. Find frequency of the letter 'a'
[EX A]: 6

[EX Q]: Sentence: 'four men standing next to each other posing for a picture'. Find frequency of the letter 'i'
[EX A]:
3