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

[EX Q]: Sentence: 'a woman holds some baked goods at the convention'. Find frequency of the letter 'd'
[EX A]: 3

[EX Q]: Sentence: 'a girl playing with a frisbee while people watch'. Find frequency of the letter 'e'
[EX A]: 5

[EX Q]: Sentence: 'the room has large windows, a wooden floor, and a king sized bed'. Find frequency of the letter 's'
[EX A]:
3