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

Q: Sentence: 'a man serving himself pizza in a wooden booth'. Find frequency of the letter 'n'

A: 4
****
Q: Sentence: 'two bears swim in a blue pool of water'. Find frequency of the letter 'o'

A: 4
****
Q: Sentence: 'an open oven containing two thick crust pizzas'. Find frequency of the letter 's'

A:
2
****