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

Sentence: 'two zebras standing around while a third zebra drinks from a pond'. Find frequency of the letter 's'
3

Sentence: 'three birds are sitting on a tree in a forest'. Find frequency of the letter 'h'
1

Sentence: 'the view of a neatly made hospital room from inside'. Find frequency of the letter 'a'

4