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

Sentence: 'small black bird with red on its head standing on a tree branch'. Find frequency of the letter 'b'
3

Sentence: 'the wooden kitchen has a small child's plastic table in it'. Find frequency of the letter 'n'
3

Sentence: 'there is a quilt and some pillows on a bed'. Find frequency of the letter 'w'

1