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

[EX Q]: Sentence: 'a baby calf has a tag on its right ear'. Find frequency of the letter 'n'
[EX A]: 1

[EX Q]: Sentence: 'two zebras feed on a plant through some wire mesh'. Find frequency of the letter 'o'
[EX A]: 4

[EX Q]: Sentence: 'a blocked-off urban city block with pedestrians walking down sidewalks on either side'. Find frequency of the letter 'i'
[EX A]:
7