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

[EX Q]: Sentence: 'a little child looking up to a camera holding a cell phone'. Find frequency of the letter 'g'
[EX A]: 2

[EX Q]: Sentence: 'two elephants walking on cement next to wall'. Find frequency of the letter 'n'
[EX A]: 5

[EX Q]: Sentence: 'a woman is trying to make a great tennis serve'. Find frequency of the letter 'w'
[EX A]:
1