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

Sentence: 'several zebras  and a giraffe in an enclosure'. Find frequency of the letter 's'
3

Sentence: 'a large grass pasture land with sheep grazing on grass'. Find frequency of the letter 'a'
7

Sentence: 'the corner counter space of a kitchen with white walls'. Find frequency of the letter 'e'

6