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

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

Sentence: 'the skateboarder is jumping over a huge statue of a shoe'. Find frequency of the letter 'i'
2

Sentence: 'a panorama of a living room and dining room'. Find frequency of the letter 'd'

2