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

Sentence: 'two zebras standing around while a third zebra drinks from a pond'. Find frequency of the letter 's'
3

Sentence: 'man in air skateboarding on street with building'. Find frequency of the letter 't'
4

Sentence: 'a carousel cake with pink and blue frosting'. Find frequency of the letter 't'
2