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

[Q]: Sentence: 'a airplane view of a big factory some people and cars'. Find frequency of the letter 'f'
[A]: 2


[Q]: Sentence: 'a family out snow skiing on a blustery day'. Find frequency of the letter 'i'
[A]: 3


[Q]: Sentence: 'six down hill skiers posing together and smiling'. Find frequency of the letter 'i'
[A]:
6