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

Sentence: 'many different species of sheep in display at a museum'. Find frequency of the letter 'h'
1

Sentence: 'people playing wii bowling in a modern library'. Find frequency of the letter 'o'
3

Sentence: 'a couple of red buses are lined up on the street'. Find frequency of the letter 'b'

1