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

Sentence: 'people fishing and enlarge mountainlake with trees lining the shoreline'. Find frequency of the letter 't'
4

Sentence: 'a group of three dogs laying on a kitchen floor'. Find frequency of the letter 'r'
3

Sentence: 'a large white passenger bus with two large rear view mirrors'. Find frequency of the letter 's'

4