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

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

Sentence: 'this marketplace has a lot of fresh fruit and vegetables'. Find frequency of the letter 'v'
1

Sentence: 'a large bird on the beach stretching its wing'. Find frequency of the letter 's'

2