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

Q: Sentence: 'a red train traveling down train tracks near a forest'. Find frequency of the letter 'f'

A: 1
****
Q: Sentence: 'a cat sprawls out and sleeps on its back on a lounge chair with an acorn theme'. Find frequency of the letter 'r'

A: 3
****
Q: Sentence: 'a book is displayed next to a white laptop'. Find frequency of the letter 'a'

A:
4
****