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

[Q]: Sentence: 'a small boat travels on the water next to the shore'. Find frequency of the letter 'a'
[A]: 5

[Q]: Sentence: 'a bed with a dog laying on it next to two laptop computers'. Find frequency of the letter 'n'
[A]: 3

[Q]: Sentence: 'some street signs on the corner of to joining streets'. Find frequency of the letter 'g'
[A]:
2