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

[EX Q]: Sentence: 'this yellow fire hydrant sits in a grass field'. Find frequency of the letter 'i'
[EX A]: 5

[EX Q]: Sentence: 'a car accident has slowed traffic as a clean up crew works'. Find frequency of the letter 'f'
[EX A]: 2

[EX Q]: Sentence: 'toy teddy bear holding a camera in its lap'. Find frequency of the letter 't'
[EX A]:
3