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

Q: Sentence: 'a young boy bouncing a tennis ball on a tennis racquet'. Find frequency of the letter 'a'

A: 5
****
Q: Sentence: 'a bed with a dog laying on it next to two laptop computers'. Find frequency of the letter 'n'

A: 3
****
Q: Sentence: 'an image of a cautionary construction sign'. Find frequency of the letter 'a'

A:
5
****