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

[EX Q]: Sentence: 'three elephants walk up a dirt trail from the water'. Find frequency of the letter 'l'
[EX A]: 3

[EX Q]: Sentence: 'a group of giraffes walk together by a hill'. Find frequency of the letter 'b'
[EX A]: 1

[EX Q]: Sentence: 'a woman on skis coming down a slope'. Find frequency of the letter 'o'
[EX A]:
5