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

Sentence: 'a little boy sitting on a bed in a bedroom'. Find frequency of the letter 'e'
3

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

Sentence: 'a cat with a stuffed lamb on its head'. Find frequency of the letter 'a'
5