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

Sentence: 'the little girl is flying her kite in the field'. Find frequency of the letter 'i'
7

Sentence: 'a black bear sitting in the grass taking a rest'. Find frequency of the letter 'a'
6

Sentence: 'a large black cat sitting on a suitcase'. Find frequency of the letter 'i'

3