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

Sentence: 'four men standing around two pizzas in a conference room'. Find frequency of the letter 't'
2

Sentence: 'a person that is looking out his window'. Find frequency of the letter 'n'
3

Sentence: 'a body of water full of boats and birds'. Find frequency of the letter 'f'

3