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

Sentence: 'pedestrian in stripe clothing standing on street corner'. Find frequency of the letter 's'
4

Sentence: 'a bowl of vegetables in a soup like substance next to a spoon'. Find frequency of the letter 'a'
5

Sentence: 'a crowd of fans watch soccer players from stadium seating'. Find frequency of the letter 'f'
3