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

[EX Q]: Sentence: 'a red fire hydrant opened and spilling water'. Find frequency of the letter 'd'
[EX A]: 4

[EX Q]: Sentence: 'bathroom scene with a black cat going behind the door'. Find frequency of the letter 'e'
[EX A]: 4

[EX Q]: Sentence: 'this is a polaroid of a man wearing a baseball cap and tie'. Find frequency of the letter 'g'
[EX A]:
1