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

Sentence: 'a doorway looking into a small bathroom with white toilet'. Find frequency of the letter 'r'
2

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

Sentence: 'a hand holding a sandwich a table and a sign'. Find frequency of the letter 'a'

8