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

Sentence: 'an orange cat sitting on the ground next to a  purse'. Find frequency of the letter 's'
2

Sentence: 'a man walking a large elephant down a dirt road'. Find frequency of the letter 'g'
2

Sentence: 'two men on bikes at the street corner'. Find frequency of the letter 'n'

3