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

Sentence: 'two laptop computers sitting on top of a white table'. Find frequency of the letter 'f'
1

Sentence: 'a group of people standing on grass with a train in the background'. Find frequency of the letter 'n'
6

Sentence: 'a group of baby elephants walk next to an adult'. Find frequency of the letter 'a'
6