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

[EX Q]: Sentence: 'small airplane in the process of taking off'. Find frequency of the letter 'e'
[EX A]: 3

[EX Q]: Sentence: 'an old glass vase containing flowers on a glass table'. Find frequency of the letter 'b'
[EX A]: 1

[EX Q]: Sentence: 'brown and white horses on the beach with the ocean in the background'. Find frequency of the letter 'd'
[EX A]:
2