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

[EX Q]: Sentence: 'a woman is looking at sheep off in a field'. Find frequency of the letter 'm'
[EX A]: 1

[EX Q]: Sentence: 'a young boy bouncing a tennis ball on a tennis racquet'. Find frequency of the letter 'a'
[EX A]: 5

[EX Q]: Sentence: 'a woman in purple shirt and white dress with sneakers and tennis racket'. Find frequency of the letter 's'
[EX A]:
6