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

[EX Q]: Sentence: 'two zebras feed on a plant through some wire mesh'. Find frequency of the letter 'o'
[EX A]: 4

[EX Q]: Sentence: 'a burning wood stove has a tea pot sitting on top of it and is full of wood'. Find frequency of the letter 'a'
[EX A]: 5

[EX Q]: Sentence: 'a man setting up a large inflatable balloon outside'. Find frequency of the letter 'm'
[EX A]:
1